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 1-5 of 5 results.

A091360 Partial sums of A000219.

Original entry on oeis.org

1, 2, 5, 11, 24, 48, 96, 182, 342, 624, 1124, 1983, 3462, 5947, 10114, 16993, 28290, 46624, 76225, 123555, 198833, 317627, 504102, 794885, 1246079, 1942112, 3010857, 4643515, 7126749, 10886361, 16555324, 25067633, 37801062, 56776035, 84951990, 126643036, 188127997, 278507781, 410949776, 604437277, 886284200, 1295668181
Offset: 0

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Author

Christian G. Bower, Jan 02 2004

Keywords

Comments

Convergent of columns of A091355.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1-x)*Product[1/(1-x^k)^k,{k,1,50}],{x,0,50}],x] (* Vaclav Kotesovec, Aug 16 2015 *)
  • PARI
    N=66; x='x+O('x^N); Vec( 1/((1-x)*prod(n=1,N, (1-x^n)^n )) ) \\ Joerg Arndt, Mar 15 2014

Formula

Euler transform of 2, 2, 3, 4, 5, 6, 7, 8, 9, ...
G.f.: 1/( (1-x) * prod(n>=1, (1-x^n)^n ) ). [Joerg Arndt, Mar 15 2014]
From Vaclav Kotesovec, Aug 16 2015: (Start)
a(n) = Sum_{k=0..n} A000219(k).
a(n) ~ (n/(2*Zeta(3)))^(1/3) * A000219(n).
a(n) ~ exp(1/12 + 3 * Zeta(3)^(1/3) * n^(2/3) / 2^(2/3)) / (A * 2^(23/36) * sqrt(3*Pi) * Zeta(3)^(5/36) * n^(13/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.
(End)
G.f.: exp(Sum_{k>=1} (sigma_2(k) + 1)*x^k/k). - Ilya Gutkovskiy, Aug 21 2018

A091356 Number of planar partitions of n with exactly 2 rows.

Original entry on oeis.org

1, 2, 5, 9, 18, 30, 53, 85, 139, 215, 336, 504, 760, 1115, 1635, 2351, 3375, 4770, 6725, 9368, 13006, 17885, 24510, 33319, 45139, 60743, 81457, 108610, 144334, 190844, 251542, 330082, 431825, 562710, 731154, 946644, 1222305, 1573155, 2019471
Offset: 2

Views

Author

Christian G. Bower, Jan 02 2004

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, add(add(min(d, k)
         *d, d=numtheory[divisors](j))*b(n-j, k), j=1..n)/n)
        end:
    a:= n-> b(n, 2)-b(n, 1):
    seq(a(n), n=2..50);  # Alois P. Heinz, Oct 02 2018
  • Mathematica
    b[n_, k_] := b[n, k] = If[n == 0, 1, Sum[Sum[Min[d, k] d, {d, Divisors[j]}] b[n - j, k], {j, 1, n}]/n];
    a[n_] :=  b[n, 2] - b[n, 1];
    a /@ Range[2, 50] (* Jean-François Alcover, Oct 28 2020, after Alois P. Heinz *)

Formula

a(n) = A000990(n) - A000041(n).

A091357 Number of planar partitions of n with exactly 3 rows.

Original entry on oeis.org

1, 2, 5, 11, 22, 42, 78, 138, 239, 405, 669, 1088, 1741, 2744, 4267, 6564, 9975, 15019, 22394, 33111, 48549, 70678, 102127, 146636, 209186, 296697, 418401, 586985, 819218, 1137962, 1573336, 2165888, 2968914, 4053563, 5512820, 7469989
Offset: 3

Views

Author

Christian G. Bower, Jan 02 2004

Keywords

Crossrefs

Column 3 of A091355.

Formula

a(n) = A000991(n)-A000990(n).

A091358 Number of planar partitions of n with exactly 4 rows.

Original entry on oeis.org

1, 2, 5, 11, 24, 46, 90, 164, 298, 520, 899, 1512, 2521, 4116, 6659, 10609, 16753, 26126, 40419, 61889, 94067, 141736, 212123, 315087, 465162, 682188, 994857, 1442340, 2080332, 2984724, 4262018, 6056849, 8569913, 12072770, 16938556
Offset: 4

Views

Author

Christian G. Bower, Jan 02 2004

Keywords

Crossrefs

Column 4 of A091355. Cf. A000219, A091356-A091360.

Formula

a(n) = A002799(n)-A000991(n).

A091359 Number of planar partitions of n with exactly 5 rows.

Original entry on oeis.org

1, 2, 5, 11, 24, 48, 94, 176, 324, 580, 1020, 1757, 2985, 4990, 8237, 13428, 21651, 34540, 54583, 85473, 132730, 204484, 312695, 474814, 716217, 1073558, 1599568, 2369781, 3491812, 5118490, 7465789, 10837964, 15661666, 22533586, 32284480
Offset: 5

Views

Author

Christian G. Bower, Jan 02 2004

Keywords

Crossrefs

Column 5 of A091355. Cf. A000219, A091356-A091360.

Formula

a(n) = A001452(n)-A002799(n).
Showing 1-5 of 5 results.