cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A306045 Expansion of e.g.f. Product_{k>=1} (1 + (exp(x) - 1)^k) / (1 - (exp(x) - 1)^k).

Original entry on oeis.org

1, 2, 10, 74, 682, 7562, 98410, 1463114, 24367402, 449039882, 9069093610, 199050295754, 4713774570922, 119735740542602, 3246094020405610, 93519923311825994, 2852458136048627242, 91805618091515859722, 3108657616523130770410, 110453876295411957125834
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 18 2018

Keywords

Comments

Convolution of A167137 and A305550.

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[(1 + (Exp[x] - 1)^k) / (1 - (Exp[x] - 1)^k), {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

Formula

a(n) = Sum_{k=0..n} Stirling2(n,k) * A015128(k) * k!.
a(n) ~ n! * exp(Pi^2 * (1 - log(2)) / (16*log(2)) + Pi * sqrt(n/(2*log(2)))) / (8*n*(log(2))^n).

A306081 Expansion of e.g.f. Product_{k>=1} ((1 + (exp(x) - 1)^k) / (1 - (exp(x) - 1)^k))^k.

Original entry on oeis.org

1, 2, 14, 134, 1574, 22262, 367814, 6907574, 144942854, 3357588662, 85000841414, 2331998188214, 68862337593734, 2176283210561462, 73250933670041414, 2614843434740912054, 98632371931151518214, 3918608865052986708662, 163507638190268814991814
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 20 2018

Keywords

Comments

Convolution of A306080 and A306046.

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[((1 + (Exp[x] - 1)^k)/(1 - (Exp[x] - 1)^k))^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

Formula

a(n) = Sum_{k=0..n} Stirling2(n,k) * A156616(k) * k!.
a(n) ~ n! * exp(3 * (7*Zeta(3))^(1/3) * n^(2/3) / (4 * log(2)^(2/3)) + (1 - log(2)) * (7*Zeta(3))^(2/3) * n^(1/3) / (8 * log(2)^(4/3)) - 7*(log(2)^2 + log(2) - 1) * Zeta(3) / (48 * log(2)^2) + 1/12) * (7*Zeta(3))^(7/36) / (A * 2^(13/12) * sqrt(3*Pi) * n^(25/36) * (log(2))^(n + 11/36)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Jun 22 2018

A330449 Expansion of e.g.f. Sum_{k>=1} (exp(x) - 1)^k / (k * (1 - (exp(x) - 1)^k)^2).

Original entry on oeis.org

1, 6, 36, 282, 2460, 25506, 299796, 3921882, 56977740, 913248786, 15917884356, 299358495882, 6066180049020, 131932872768066, 3057940695635316, 75151035318996282, 1954299203147952300, 53684552455571903346, 1553161560008013680676, 47162101103528811791082
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 15 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Sum[(Exp[x] - 1)^k/(k (1 - (Exp[x] - 1)^k)^2), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]! // Rest
    Table[Sum[StirlingS2[n, k] (k - 1)! DivisorSigma[2, k], {k, 1, n}], {n, 1, 20}]

Formula

E.g.f.: -Sum_{k>=1} k * log(1 - (exp(x) - 1)^k).
E.g.f.: A(x) = log(B(x)), where B(x) = e.g.f. of A306046.
G.f.: Sum_{k>=1} (k - 1)! * sigma_2(k) * x^k / Product_{j=1..k} (1 - j*x), where sigma_2 = A001157.
exp(Sum_{n>=1} a(n) * log(1 + x)^n / n!) = g.f. of A000219.
a(n) = Sum_{k=1..n} Stirling2(n,k) * (k - 1)! * sigma_2(k).
a(n) ~ n! * zeta(3) * n / (4 * (log(2))^(n+2)). - Vaclav Kotesovec, Dec 15 2019

A306080 Expansion of e.g.f. Product_{k>=1} (1 + (exp(x) - 1)^k)^k.

Original entry on oeis.org

1, 1, 5, 43, 401, 4651, 64265, 1015603, 17996081, 354373531, 7682286425, 181466541763, 4632985312961, 127068851847211, 3724903637434985, 116185013450349523, 3840969677266089041, 134113334651486325691, 4930511086446971405945, 190327859758408148070883
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 20 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[(1 + (Exp[x] - 1)^k)^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

Formula

a(n) = Sum_{k=0..n} Stirling2(n,k) * A026007(k) * k!.
a(n) ~ n! * exp(3^(4/3) * Zeta(3)^(1/3) * n^(2/3) / (4 * log(2)^(2/3)) + (1 - log(2)) * (3*Zeta(3))^(2/3) * n^(1/3) / (8 * log(2)^(4/3)) - (log(2)^2 + log(2) - 1) * Zeta(3) / (16 * log(2)^2)) * Zeta(3)^(1/6) / (2^(13/12) * 3^(1/3) * sqrt(Pi) * n^(2/3) * (log(2))^(n + 1/3)). - Vaclav Kotesovec, Jun 23 2018
Showing 1-4 of 4 results.