Evaluation of Euler-type sum $displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}$ [closed]
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How can one evaluate the sum $displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}$? Here $H_{n}$ denotes $n$-th harmonic number.
real-analysis sequences-and-series summation euler-sums
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closed as off-topic by amWhy, Masacroso, Clarinetist, RRL, user10354138 Dec 7 '18 at 2:40
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – amWhy, Masacroso, Clarinetist, RRL, user10354138
If this question can be reworded to fit the rules in the help center, please edit the question.
add a comment |
$begingroup$
How can one evaluate the sum $displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}$? Here $H_{n}$ denotes $n$-th harmonic number.
real-analysis sequences-and-series summation euler-sums
$endgroup$
closed as off-topic by amWhy, Masacroso, Clarinetist, RRL, user10354138 Dec 7 '18 at 2:40
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – amWhy, Masacroso, Clarinetist, RRL, user10354138
If this question can be reworded to fit the rules in the help center, please edit the question.
1
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What sum will come next?
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– gammatester
Dec 6 '18 at 22:57
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with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
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– Masacroso
Dec 6 '18 at 23:18
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$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
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– user178256
Dec 7 '18 at 8:49
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How can this be proven?
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– Isak
Dec 7 '18 at 10:23
add a comment |
$begingroup$
How can one evaluate the sum $displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}$? Here $H_{n}$ denotes $n$-th harmonic number.
real-analysis sequences-and-series summation euler-sums
$endgroup$
How can one evaluate the sum $displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}$? Here $H_{n}$ denotes $n$-th harmonic number.
real-analysis sequences-and-series summation euler-sums
real-analysis sequences-and-series summation euler-sums
asked Dec 6 '18 at 22:52
IsakIsak
215
215
closed as off-topic by amWhy, Masacroso, Clarinetist, RRL, user10354138 Dec 7 '18 at 2:40
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – amWhy, Masacroso, Clarinetist, RRL, user10354138
If this question can be reworded to fit the rules in the help center, please edit the question.
closed as off-topic by amWhy, Masacroso, Clarinetist, RRL, user10354138 Dec 7 '18 at 2:40
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – amWhy, Masacroso, Clarinetist, RRL, user10354138
If this question can be reworded to fit the rules in the help center, please edit the question.
1
$begingroup$
What sum will come next?
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– gammatester
Dec 6 '18 at 22:57
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with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
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– Masacroso
Dec 6 '18 at 23:18
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$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
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– user178256
Dec 7 '18 at 8:49
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How can this be proven?
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– Isak
Dec 7 '18 at 10:23
add a comment |
1
$begingroup$
What sum will come next?
$endgroup$
– gammatester
Dec 6 '18 at 22:57
$begingroup$
with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
$endgroup$
– Masacroso
Dec 6 '18 at 23:18
$begingroup$
$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
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– user178256
Dec 7 '18 at 8:49
$begingroup$
How can this be proven?
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– Isak
Dec 7 '18 at 10:23
1
1
$begingroup$
What sum will come next?
$endgroup$
– gammatester
Dec 6 '18 at 22:57
$begingroup$
What sum will come next?
$endgroup$
– gammatester
Dec 6 '18 at 22:57
$begingroup$
with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
$endgroup$
– Masacroso
Dec 6 '18 at 23:18
$begingroup$
with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
$endgroup$
– Masacroso
Dec 6 '18 at 23:18
$begingroup$
$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
$endgroup$
– user178256
Dec 7 '18 at 8:49
$begingroup$
$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
$endgroup$
– user178256
Dec 7 '18 at 8:49
$begingroup$
How can this be proven?
$endgroup$
– Isak
Dec 7 '18 at 10:23
$begingroup$
How can this be proven?
$endgroup$
– Isak
Dec 7 '18 at 10:23
add a comment |
1 Answer
1
active
oldest
votes
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$$sum_{ngeq 1}H_n^2 x^n = frac{log^2(1-x)+text{Li}_2(x)}{1-x}$$
hence the explicit computation of your series is equivalent to the computation of
$$ int_{0}^{1}frac{log^2(1-x^2)+text{Li}_2(x^2)}{1-x^2}log(x),dx $$
which can probably be tackled through Fourier(-Legendre) series. The simple part is
$$ int_{0}^{1}frac{log^2(1-x^2)log(x)}{1-x^2},dx = -frac{pi^4}{24}-frac{pi^2}{2}log^2(2)+7zeta(3)log(2).$$
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Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
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– Badam Baplan
Dec 6 '18 at 23:33
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Thank You, that is something yet. Any ideas about the second part?
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– Isak
Dec 6 '18 at 23:33
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@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
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– Jack D'Aurizio
Dec 6 '18 at 23:36
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nice, thanks for explaining. this is a nice approach.
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– Badam Baplan
Dec 6 '18 at 23:38
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@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
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– Jack D'Aurizio
Dec 6 '18 at 23:39
|
show 1 more comment
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
$$sum_{ngeq 1}H_n^2 x^n = frac{log^2(1-x)+text{Li}_2(x)}{1-x}$$
hence the explicit computation of your series is equivalent to the computation of
$$ int_{0}^{1}frac{log^2(1-x^2)+text{Li}_2(x^2)}{1-x^2}log(x),dx $$
which can probably be tackled through Fourier(-Legendre) series. The simple part is
$$ int_{0}^{1}frac{log^2(1-x^2)log(x)}{1-x^2},dx = -frac{pi^4}{24}-frac{pi^2}{2}log^2(2)+7zeta(3)log(2).$$
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$begingroup$
Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
|
show 1 more comment
$begingroup$
$$sum_{ngeq 1}H_n^2 x^n = frac{log^2(1-x)+text{Li}_2(x)}{1-x}$$
hence the explicit computation of your series is equivalent to the computation of
$$ int_{0}^{1}frac{log^2(1-x^2)+text{Li}_2(x^2)}{1-x^2}log(x),dx $$
which can probably be tackled through Fourier(-Legendre) series. The simple part is
$$ int_{0}^{1}frac{log^2(1-x^2)log(x)}{1-x^2},dx = -frac{pi^4}{24}-frac{pi^2}{2}log^2(2)+7zeta(3)log(2).$$
$endgroup$
$begingroup$
Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
|
show 1 more comment
$begingroup$
$$sum_{ngeq 1}H_n^2 x^n = frac{log^2(1-x)+text{Li}_2(x)}{1-x}$$
hence the explicit computation of your series is equivalent to the computation of
$$ int_{0}^{1}frac{log^2(1-x^2)+text{Li}_2(x^2)}{1-x^2}log(x),dx $$
which can probably be tackled through Fourier(-Legendre) series. The simple part is
$$ int_{0}^{1}frac{log^2(1-x^2)log(x)}{1-x^2},dx = -frac{pi^4}{24}-frac{pi^2}{2}log^2(2)+7zeta(3)log(2).$$
$endgroup$
$$sum_{ngeq 1}H_n^2 x^n = frac{log^2(1-x)+text{Li}_2(x)}{1-x}$$
hence the explicit computation of your series is equivalent to the computation of
$$ int_{0}^{1}frac{log^2(1-x^2)+text{Li}_2(x^2)}{1-x^2}log(x),dx $$
which can probably be tackled through Fourier(-Legendre) series. The simple part is
$$ int_{0}^{1}frac{log^2(1-x^2)log(x)}{1-x^2},dx = -frac{pi^4}{24}-frac{pi^2}{2}log^2(2)+7zeta(3)log(2).$$
answered Dec 6 '18 at 23:31
Jack D'AurizioJack D'Aurizio
288k33280659
288k33280659
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Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
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– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
|
show 1 more comment
$begingroup$
Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
$begingroup$
Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Isn't this summing $H_n^2/(2n+1)$ as opposed to $H_n^2/(2n+1)^2$?
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
Thank You, that is something yet. Any ideas about the second part?
$endgroup$
– Isak
Dec 6 '18 at 23:33
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
@BadamBaplan: it is summing the right thing, since $int_{0}^{1}x^{2n}log(x),dx = -frac{1}{(2n+1)^2}$.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:36
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
nice, thanks for explaining. this is a nice approach.
$endgroup$
– Badam Baplan
Dec 6 '18 at 23:38
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
$begingroup$
@Isak: the difficult part is essentially $sum_{ngeq 1}frac{H_n^{(2)}}{(2n+1)^2}$ which appears to be manageable by summation by parts.
$endgroup$
– Jack D'Aurizio
Dec 6 '18 at 23:39
|
show 1 more comment
1
$begingroup$
What sum will come next?
$endgroup$
– gammatester
Dec 6 '18 at 22:57
$begingroup$
with a software and a computer? Wolfram Mathematica gives the approximate result of $0.880734$
$endgroup$
– Masacroso
Dec 6 '18 at 23:18
$begingroup$
$displaystylesum_{n=1}^{infty}frac{H_{n}^{2}}{(2n+1)^{2}}=8Li_4(frac{1}{2})+frac{pi^2}{6}ln^22+frac{1}{3}ln^42-frac{61}{1440}{pi^4}$
$endgroup$
– user178256
Dec 7 '18 at 8:49
$begingroup$
How can this be proven?
$endgroup$
– Isak
Dec 7 '18 at 10:23