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.

A294591 Expansion of Product_{k>=1} 1/((1 - x^(2*k-1))^(k*(3*k-1)/2)*(1 - x^(2*k))^(k*(3*k+1)/2)).

Original entry on oeis.org

1, 1, 3, 8, 18, 40, 88, 184, 384, 783, 1573, 3110, 6087, 11745, 22450, 42466, 79597, 147890, 272632, 498696, 905846, 1634270, 2929804, 5220581, 9249440, 16297659, 28567571, 49825296, 86487331, 149438681, 257077485, 440378787, 751313413, 1276765557, 2161511352
Offset: 0

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Author

Ilya Gutkovskiy, Nov 05 2017

Keywords

Comments

Euler transform of the generalized pentagonal numbers (A001318).

Crossrefs

Programs

  • Mathematica
    nmax = 34; CoefficientList[Series[Product[1/((1 - x^(2 k - 1))^(k (3 k - 1)/2) (1 - x^(2 k))^(k (3 k + 1)/2)), {k, 1, nmax}], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d Ceiling[d/2] Ceiling[(3 d + 1)/2]/2, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 34}]

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^A001318(k).
a(n) ~ exp(Pi * 2^(5/4) / (3*5^(1/4)) * n^(3/4) + 3*Zeta(3) * sqrt(5*n) / (2^(3/2) * Pi^2) + (Pi/48 - 45*Zeta(3)^2 / (8*Pi^5)) * (5*n/2)^(1/4) + 225*Zeta(3)^3 / (8*Pi^8) - 11*Zeta(3) / (64*Pi^2))/ (2^(95/48) * 5^(1/8) * n^(5/8)). - Vaclav Kotesovec, Nov 07 2017

A294654 Expansion of Product_{k>=1} 1/((1 - x^(2*k-1))^(k*(5*k-3)/2)*(1 - x^(2*k))^(k*(5*k+3)/2)).

Original entry on oeis.org

1, 1, 5, 12, 35, 81, 208, 475, 1123, 2505, 5617, 12192, 26368, 55797, 117255, 242660, 498126, 1010515, 2033662, 4053214, 8017622, 15729219, 30643069, 59268267, 113898873, 217480476, 412813600, 779042099, 1462188257, 2729852845, 5070966794, 9373909586, 17247473718
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 06 2017

Keywords

Comments

Euler transform of the generalized heptagonal numbers (A085787).

Crossrefs

Programs

  • Mathematica
    nmax = 32; CoefficientList[Series[Product[1/((1 - x^(2 k - 1))^(k (5 k - 3)/2) (1 - x^(2 k))^(k (5 k + 3)/2)), {k, 1, nmax}], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d (5 d (d + 1)/8 + (-1)^d (2 d + 1)/16 - 1/16), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 32}]

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^A085787(k).
a(n) ~ exp(Pi * (2/3)^(5/4) * n^(3/4) + 5*Zeta(3) * sqrt(3*n) / (2^(3/2) * Pi^2) - (75*3^(1/4) * Zeta(3)^2 / (2^(13/4) * Pi^5) + Pi / (2^(17/4) * 3^(3/4))) * n^(1/4) + 375 * Zeta(3)^3 / (8*Pi^8) - 5*Zeta(3) / (64*Pi^2) + 1/12) * Pi^(1/12) / (A * 2^(11/6) * 3^(7/48) * n^(31/48)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Nov 07 2017

A294691 Expansion of Product_{k>=1} 1 / (1 - x^(2*k - 1))^(k*(3*k - 2)).

Original entry on oeis.org

1, 1, 1, 9, 9, 30, 66, 106, 274, 459, 1010, 1862, 3552, 6973, 12446, 24245, 43041, 80372, 144482, 259633, 468047, 822642, 1468714, 2556542, 4493704, 7782441, 13470564, 23204471, 39679759, 67855411, 115004992, 194984378, 328183865, 551595570, 922663665
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 07 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1/(1-x^(2*k-1))^(k*(3*k-2)), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ exp(Pi * 2^(5/4) / (3*5^(1/4)) * n^(3/4) + Zeta(3) * sqrt(5*n) / (Pi^2 * sqrt(2)) - (5*Zeta(3)^2 / (2*Pi^5) + Pi/24) * (5*n/2)^(1/4) + 25*Zeta(3)^3 / (3*Pi^8) + 2*Zeta(3) / (3*Pi^2) - 1/24) * sqrt(A) / (2^(173/96) * 5^(11/96) * Pi^(1/24) * n^(59/96)), where A is the Glaisher-Kinkelin constant A074962.

A294692 Expansion of Product_{k>=1} 1 / (1 - x^k)^(k*(3*k + 2)).

Original entry on oeis.org

1, 5, 31, 148, 667, 2754, 10823, 40393, 145085, 502780, 1690603, 5530649, 17658430, 55141520, 168751779, 506933980, 1496999360, 4350994324, 12460305177, 35192973824, 98116587875, 270220568883, 735668636567, 1981082952258, 5279879097853, 13933764841202
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 07 2017

Keywords

Crossrefs

Programs

  • Maple
    N:= 50:
    S:= series(mul(1/(1-x^k)^(k*(3*k+2)), k=1..N),x,N+1):
    seq(coeff(S,x,n),n=0..N); # Robert Israel, Nov 07 2017
  • Mathematica
    nmax = 30; CoefficientList[Series[Product[1/(1-x^k)^(k*(3*k+2)), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ exp(4*Pi*n^(3/4) / (3*5^(1/4)) + 2*Zeta(3) * sqrt(5*n) / Pi^2 - 2*5^(5/4) * Zeta(3)^2 * n^(1/4) / Pi^5 + 200*Zeta(3)^3 / (3*Pi^8) - 3*Zeta(3) / (4*Pi^2) + 1/6) * Pi^(1/6) / (A^2 * 2^(3/2) * 5^(1/6) * n^(2/3)), where A is the Glaisher-Kinkelin constant A074962.
Showing 1-4 of 4 results.