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 1-10 of 17 results. Next

A262736 Expansion of Product_{k>=1} (1 + x^(2*k-1))^(2*k-1).

Original entry on oeis.org

1, 1, 0, 3, 3, 5, 8, 10, 22, 25, 41, 57, 88, 126, 168, 261, 351, 512, 685, 984, 1357, 1865, 2566, 3485, 4838, 6459, 8832, 11831, 16056, 21404, 28660, 38259, 50875, 67613, 89161, 118184, 155321, 204609, 267708, 351125, 458331, 597740, 777590, 1010020, 1310390
Offset: 0

Views

Author

Vaclav Kotesovec, Sep 29 2015

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[Product[(1 + x^(2*k-1))^(2*k-1), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ exp(3^(4/3) * (Zeta(3))^(1/3) * n^(2/3) / 2^(5/3)) * Zeta(3)^(1/6) / (2^(3/4) * 3^(1/3) * sqrt(Pi) * n^(2/3)).

A285069 Expansion of Product_{k>=1} (1 - x^(2*k-1))^(2*k-1).

Original entry on oeis.org

1, -1, 0, -3, 3, -5, 8, -10, 22, -25, 41, -57, 88, -126, 168, -261, 351, -512, 685, -984, 1357, -1865, 2566, -3485, 4838, -6459, 8832, -11831, 16056, -21404, 28660, -38259, 50875, -67613, 89161, -118184, 155321, -204609, 267708, -351125, 458331, -597740
Offset: 0

Views

Author

Seiichi Manyama, Apr 09 2017

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[Product[(1 - x^(2k-1))^(2k-1), {k, 50}], {x, 0, 50}], x] (* Indranil Ghosh, Apr 09 2017 *)
  • PARI
    N=66; x='x+O('x^N); Vec(exp(-sum(k=1, N, sumdiv(k, d, d^2*(d%2))*x^k/k))) \\ Seiichi Manyama, Oct 31 2017

Formula

a(n) = (-1)^n * A262736(n).
a(0) = 1, a(n) = -(1/n)*Sum_{k=1..n} A050999(k)*a(n-k) for n > 0.
a(n) ~ (-1)^n * exp(3^(4/3) * (Zeta(3))^(1/3) * n^(2/3) / 2^(5/3)) * Zeta(3)^(1/6) / (2^(3/4) * 3^(1/3) * sqrt(Pi) * n^(2/3)). - Vaclav Kotesovec, Nov 09 2017

A262946 Expansion of Product_{k>=1} 1/(1-x^(3*k-1))^(3*k-1).

Original entry on oeis.org

1, 0, 2, 0, 3, 5, 4, 10, 13, 15, 37, 31, 61, 87, 99, 178, 228, 286, 477, 552, 816, 1163, 1418, 2077, 2790, 3507, 5113, 6478, 8563, 11888, 15005, 20100, 27054, 34055, 46002, 59905, 76436, 102105, 130879, 168103, 221954, 281300, 363743, 472557, 597579, 772148
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 05 2015

Keywords

Comments

A262946(n)/A262947(n) ~ exp(3*(d1-d2)) * Gamma(1/3)^3 / (2*Pi)^(3/2), where d1 = A263030 and d2 = A263031. - Vaclav Kotesovec, Oct 08 2015

Crossrefs

Programs

  • Maple
    with(numtheory):
    a:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          `if`(irem(d+3, 3, 'r')=2, 3*r-1, 0),
           d=divisors(j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..45);  # Alois P. Heinz, Oct 05 2015
  • Mathematica
    nmax=60; CoefficientList[Series[Product[1/((1-x^(3k-1))^(3k-1)),{k,1,nmax}],{x,0,nmax}],x]
    nmax=60; CoefficientList[Series[E^Sum[1/j*x^(2*j)*(2+x^(3*j))/(1-x^(3*j))^2, {j, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ (2*Zeta(3))^(5/36) * exp(3*d1 + (3/2)^(2/3) * Zeta(3)^(1/3) * n^(2/3)) / (3^(29/36) * Gamma(2/3) * n^(23/36)), where d1 = A263030 = Integral_{x=0..infinity} 1/x*(exp(-2*x)/(1 - exp(-3*x))^2 - 1/(9*x^2) - 1/(9*x) + exp(-x)/36) = -0.18870819197952853237641009864920797359211446726842922150941... . - Vaclav Kotesovec, Oct 08 2015

A284628 Expansion of Product_{k>=1} 1/(1+x^(2*k-1))^(2*k-1).

Original entry on oeis.org

1, -1, 1, -4, 4, -9, 15, -22, 37, -56, 92, -133, 210, -310, 466, -696, 1013, -1495, 2160, -3141, 4495, -6462, 9172, -13024, 18387, -25840, 36213, -50500, 70280, -97302, 134522, -185105, 254245, -347938, 475036, -646676, 878145, -1189468, 1607095, -2166672, 2913794
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[1/(1+x^(2*k-1))^(2*k-1), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 15 2017 *)

Formula

a(n) = (-1)^n * A262811(n).

A281781 Expansion of Product_{k>=1} (1 - x^(2*k))^(2*k)/(1 - x^(2*k-1))^(2*k-1).

Original entry on oeis.org

1, 1, -1, 2, -1, -2, 6, -6, 3, -1, -1, 9, -18, 23, -27, 23, -1, -24, 49, -89, 121, -117, 96, -60, -18, 138, -275, 408, -525, 592, -566, 444, -181, -276, 854, -1485, 2154, -2765, 3157, -3131, 2571, -1468, -301, 2813, -5860, 9153, -12386, 15082, -16664, 16558, -14125
Offset: 0

Views

Author

Seiichi Manyama, Apr 14 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[(1 - x^(2*k))^(2*k)/(1 - x^(2*k-1))^(2*k-1), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 09 2017 *)
    nmax = 50; CoefficientList[Series[Product[(1 - x^(2*k))^(4*k)/(1 - x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 09 2017 *)
    nmax = 50; CoefficientList[Series[Product[(1 + x^k)^(4*k)*(1 - x^k)^(3*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 09 2017 *)
  • PARI
    x='x+O('x^51); Vec(prod(k=1, 50, (1 - x^(2*k))^(2*k)/(1 - x^(2*k-1))^(2*k-1))) \\ Indranil Ghosh, Apr 14 2017

Formula

G.f.: exp(Sum_{k>=1} x^k/(k*(1 + x^k)^2)). - Ilya Gutkovskiy, May 28 2018

A263199 Expansion of Product_{k>=1} 1/(1 - x^(2*k+1))^(2*k+1).

Original entry on oeis.org

1, 0, 0, 3, 0, 5, 6, 7, 15, 19, 36, 41, 77, 100, 156, 230, 317, 482, 665, 981, 1354, 1967, 2710, 3852, 5363, 7453, 10373, 14287, 19780, 27022, 37220, 50583, 69140, 93693, 127098, 171640, 231469, 311323, 417627, 559577, 747122, 996947, 1325872, 1761900
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 12 2015

Keywords

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          `if`(d::even, 0, d), d=divisors(j))*b(n-j), j=1..n)/n)
        end:
    seq(b(n)-b(n-1), n=0..60);  # after Alois P. Heinz
  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1/(1 - x^(2*k+1))^(2*k+1),{k,1,nmax}],{x,0,nmax}],x]

Formula

For n>1, a(n) = A262811(n) - A262811(n-1).
a(n) ~ A * Zeta(3)^(17/36) * exp(-1/12 + 3 * Zeta(3)^(1/3) * n^(2/3)/2) / (2^(2/3) * sqrt(3*Pi) * n^(35/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.

A285048 Expansion of Product_{k>=0} 1/(1-x^(4*k+1))^(4*k+1).

Original entry on oeis.org

1, 1, 1, 1, 1, 6, 6, 6, 6, 15, 30, 30, 30, 43, 88, 123, 123, 140, 250, 385, 455, 476, 678, 1098, 1413, 1564, 1913, 2918, 4048, 4707, 5452, 7572, 10747, 13265, 15195, 19534, 27349, 35146, 41042, 50011, 67596, 88897, 106519, 126635, 164230, 216862, 266473, 314883
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2017

Keywords

Crossrefs

Product_{k>=0} 1/(1-x^(m*k+1))^(m*k+1): A262811 (m=2), A262947 (m=3), this sequence (m=4), A285049 (m=5).

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[1/(1-x^(4*k-3))^(4*k-3), {k,1,nmax}], {x,0,nmax}], x] (* Vaclav Kotesovec, Apr 16 2017 *)

Formula

a(n) ~ 4 * Pi * 2^(25/72) * Zeta(3)^(11/72) * exp(4*c + 3 * 2^(-4/3) * Zeta(3)^(1/3) * n^(2/3)) / (sqrt(3) * Gamma(1/4)^3 * n^(47/72)), where c = Integral_{x=0..inf} ((-19/(exp(x)*96) + 1/(exp(x)*(1 - exp(-4*x))^2) - 1/(16*x^2) - 3/(16*x))/x) dx = 0.09601010361866957956805888476415949391295401812706635... - Vaclav Kotesovec, Apr 16 2017

A285131 Expansion of Product_{k>=0} 1/(1-x^(4*k+3))^(4*k+3).

Original entry on oeis.org

1, 0, 0, 3, 0, 0, 6, 7, 0, 10, 21, 11, 15, 42, 61, 36, 70, 150, 150, 124, 278, 441, 375, 468, 909, 1131, 1018, 1581, 2602, 2810, 2947, 4819, 6768, 6980, 8509, 13389, 16788, 17609, 23722, 34720, 40337, 44863, 63128, 85430, 95887, 114037, 159882, 202699, 227087
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2017

Keywords

Crossrefs

Product_{k>=0} 1/(1-x^(m*k+m-1))^(m*k+m-1): A262811 (m=2), A262946 (m=3), this sequence (m=4), A285132 (m=5).
Cf. A285213.

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1/(1-x^(4*k+3))^(4*k+3), {k,0,nmax}], {x,0,nmax}], x] (* Vaclav Kotesovec, Apr 15 2017 *)
  • PARI
    x='x+O('x^100); Vec(prod(k=0, 100, 1/(1 - x^(4*k + 3))^(4*k + 3))) \\ Indranil Ghosh, Apr 15 2017

Formula

a(n) ~ exp(4*c + 3 * 2^(-4/3) * Zeta(3)^(1/3) * n^(2/3)) * Zeta(3)^(11/72) / (2^(47/72) * sqrt(3) * Gamma(3/4) * n^(47/72)), where c = Integral_{x=0..inf} ((5/(exp(x)*96) + 1/(exp(3*x)*(1 - exp(-4*x))^2) - 1/(16*x^2) - 1/(16*x))/x) dx = -0.158924147180165035059952001737321408554746599955833696821824808... - Vaclav Kotesovec, Apr 15 2017

A285215 Expansion of Product_{k>=1} (1 - x^(4*k))^(4*k) / (1 - x^k)^k.

Original entry on oeis.org

1, 1, 3, 6, 9, 20, 36, 62, 106, 184, 302, 503, 829, 1325, 2119, 3367, 5282, 8227, 12740, 19550, 29849, 45300, 68325, 102495, 152998, 227249, 336005, 494597, 724875, 1058213, 1538860, 2229370, 3218304, 4630015, 6638728, 9488894, 13520995, 19208916, 27211430
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2017

Keywords

Crossrefs

Product_{k>=1} (1 - x^(m*k))^(m*k)/(1 - x^k)^k: A262811 (m=2), A262923 (m=3), this sequence (m=4), A285246 (m=5).

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[1 / ((1-x^(4*k+1))^(4*k+1) * (1-x^(4*k+2))^(4*k+2) * (1-x^(4*k+3))^(4*k+3)), {k,0,nmax}], {x,0,nmax}], x] (* Vaclav Kotesovec, Apr 15 2017 *)
    nmax = 50; CoefficientList[Series[Product[(1 - x^(4*k))^(4*k)/((1 - x^k)^k), {k,1,nmax}], {x,0,nmax}], x] (* Vaclav Kotesovec, Apr 15 2017 *)
  • PARI
    x='x+O('x^100); Vec(prod(k=0, 100, 1 / ((1 - x^(4*k + 1))^(4*k + 1)*(1 - x^(4*k + 2))^(4*k + 2)*(1 - x^(4*k + 3))^(4*k + 3)))) \\ Indranil Ghosh, Apr 15 2017

Formula

G.f.: Product_{k>=0} 1 / ((1-x^(4*k+1))^(4*k+1) * (1-x^(4*k+2))^(4*k+2) * (1-x^(4*k+3))^(4*k+3)).
a(n) ~ exp(-1/4 + 2^(-4/3) * 3^(4/3) * Zeta(3)^(1/3) * n^(2/3)) * A^3 * Zeta(3)^(1/12) / (2^(5/4) * 3^(5/12) * sqrt(Pi) * n^(7/12)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Apr 16 2017

A292038 Expansion of Product_{k>=1} ((1 + x^(2*k-1)) / (1 - x^(2*k-1)))^(2*k-1).

Original entry on oeis.org

1, 2, 2, 8, 14, 24, 52, 84, 158, 274, 464, 800, 1316, 2208, 3576, 5832, 9358, 14876, 23614, 36936, 57752, 89336, 137716, 210844, 321148, 486890, 733912, 1102336, 1646736, 2451464, 3632832, 5363988, 7889710, 11562712, 16888748, 24581904, 35670242, 51591096
Offset: 0

Views

Author

Vaclav Kotesovec, Sep 08 2017

Keywords

Comments

Convolution of A262736 and A262811.

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[((1+x^(2*k-1))/(1-x^(2*k-1)))^(2*k-1), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ exp(3*(7*Zeta(3))^(1/3)*n^(2/3) / 2^(5/3) - 1/12) * A * (7*Zeta(3))^(5/36) / (2^(31/36) * sqrt(3*Pi) * n^(23/36)), where A is the Glaisher-Kinkelin constant A074962.
G.f.: exp(2*Sum_{k>=1} sigma_2(2*k - 1)*x^(2*k-1)/(2*k - 1)). - Ilya Gutkovskiy, Apr 19 2019
Showing 1-10 of 17 results. Next