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 1-3 of 3 results.

A294609 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} 1/(1-j*x^j)^(j^(k*j)) in powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 9, 6, 1, 1, 33, 90, 14, 1, 1, 129, 2220, 1154, 25, 1, 1, 513, 59178, 264908, 17427, 56, 1, 1, 2049, 1594836, 67176362, 49163017, 309117, 97, 1, 1, 8193, 43048770, 17181595604, 152662625259, 13120646934, 6285102, 198
Offset: 0

Views

Author

Seiichi Manyama, Nov 04 2017

Keywords

Examples

			Square array begins:
    1,    1,      1,        1,           1, ...
    1,    1,      1,        1,           1, ...
    3,    9,     33,      129,         513, ...
    6,   90,   2220,    59178,     1594836, ...
   14, 1154, 264908, 67176362, 17181595604, ...
		

Crossrefs

Columns k=0..2 give A006906, A294610, A294611.
Rows n=0-1 give A000012.
Cf. A294605.

Formula

A(0,k) = 1 and A(n,k) = (1/n) * Sum_{j=1..n} (Sum_{d|j} d^(k*d+1+j/d)) * A(n-j,k) for n > 0.

A294606 Expansion of Product_{k>=1} (1 - k*x^k)^(k^k).

Original entry on oeis.org

1, -1, -8, -73, -919, -13977, -253640, -5290184, -124681406, -3272865905, -94671665085, -2991846831531, -102566663464544, -3791541404744714, -150357943095635464, -6367699625807475503, -286854179220742344135, -13697182490105378305606
Offset: 0

Views

Author

Seiichi Manyama, Nov 04 2017

Keywords

Crossrefs

Column k=1 of A294605.
Cf. A294608.

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[(1 - k*x^k)^(k^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 05 2017 *)
  • PARI
    N=66; x='x+O('x^N); Vec(prod(k=1, N, (1-k*x^k)^k^k))

Formula

a(0) = 1 and a(n) = -(1/n) * Sum_{k=1..n} A294608(k) * a(n-k) for n > 0.

A294607 Expansion of Product_{k>=1} (1 - k*x^k)^(k^(2*k)).

Original entry on oeis.org

1, -1, -32, -2155, -259477, -48496477, -13001163543, -4732376829091, -2246495500625034, -1348407234549297356, -998562296547665810106, -894380299878766527522232, -953030926136814034550634393, -1191548000252369142490485950437
Offset: 0

Views

Author

Seiichi Manyama, Nov 04 2017

Keywords

Crossrefs

Column k=2 of A294605.

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[(1 - k*x^k)^(k^(2*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 05 2017 *)
  • PARI
    N=20; x='x+O('x^N); Vec(prod(k=1, N, (1-k*x^k)^k^(2*k)))
Showing 1-3 of 3 results.