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.

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A294704 Expansion of Product_{k>=1} (1 - k^k*x^k)^(k^k).

Original entry on oeis.org

1, -1, -16, -713, -64711, -9688521, -2165724176, -675843638952, -280752881225790, -149800127712465769, -99844730464906330029, -81300082264515781043363, -79413710307214816810372248, -91652445696245266803423194130
Offset: 0

Views

Author

Seiichi Manyama, Nov 07 2017

Keywords

Crossrefs

Column k=1 of A294699.

Programs

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

Formula

a(0) = 1 and a(n) = -(1/n) * Sum_{k=1..n} A294773(k)*a(n-k) for n > 0.
a(n) ~ -n^(2*n). - Vaclav Kotesovec, Nov 09 2017

A294756 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^(k*j)*x^j)^j(k*j) in powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 17, 3, 1, 1, 257, 746, 5, 1, 1, 4097, 531698, 66442, 7, 1, 1, 65537, 387424586, 4295533810, 9843731, 11, 1, 1, 1048577, 282429602018, 281475372654922, 95371863223331, 2187951485, 15, 1, 1, 16777217, 205891133143226, 18446744358295025890, 931322857677725493491, 4738477951108288824, 680615166718, 22
Offset: 0

Views

Author

Seiichi Manyama, Nov 08 2017

Keywords

Examples

			Square array begins:
   1,     1,          1,               1, ...
   1,     1,          1,               1, ...
   2,    17,        257,            4097, ...
   3,   746,     531698,       387424586, ...
   5, 66442, 4295533810, 281475372654922, ...
		

Crossrefs

Columns k=0..1 give A000041, A294757.
Rows n=0-1 give A000012.
Cf. A294699.

Formula

A(0,k) = 1 and A(n,k) = (1/n) * Sum_{j=1..n} (Sum_{d|j} d^(1+k*(d+j))) * A(n-j,k) for n > 0.
Showing 1-2 of 2 results.