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.

A290216 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. Product_{i>0} (1 + Sum_{j=1..k} j*x^(j*i)).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 3, 2, 0, 1, 1, 3, 2, 2, 0, 1, 1, 3, 5, 6, 3, 0, 1, 1, 3, 5, 6, 7, 4, 0, 1, 1, 3, 5, 10, 10, 12, 5, 0, 1, 1, 3, 5, 10, 10, 18, 13, 6, 0, 1, 1, 3, 5, 10, 15, 22, 25, 22, 8, 0, 1, 1, 3, 5, 10, 15, 22, 29, 34, 26, 10, 0, 1, 1, 3, 5
Offset: 0

Views

Author

Seiichi Manyama, Oct 06 2017

Keywords

Examples

			Square array begins:
   1, 1, 1,  1,  1, ...
   0, 1, 1,  1,  1, ...
   0, 1, 3,  3,  3, ...
   0, 2, 2,  5,  5, ...
   0, 2, 6,  6, 10, ...
   0, 3, 7, 10, 10, ...
		

Crossrefs

Columns k=0..3 give A000007, A000009, A293204, A290269.
Rows n=0 gives A000012.
Main diagonal gives A077285.
Product_{i>0} (1 + Sum_{j=1..k} j*x^(j*i))^m: A290217 (m=-1), this sequence (m=1), A293377 (m=2).
Cf. A293305.

A293378 Expansion of (eta(q^6)/(eta(q)*eta(q^2)*eta(q^3)))^2 in powers of q.

Original entry on oeis.org

1, 2, 7, 16, 39, 80, 171, 328, 638, 1168, 2133, 3744, 6540, 11092, 18687, 30816, 50421, 81136, 129582, 204160, 319340, 493952, 758781, 1154624, 1745748, 2617958, 3902614, 5776144, 8501784, 12434320, 18092565, 26175784, 37689734, 53989056, 76993497, 109284736
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[((1 + x^(3*k))/((1 - x^k)*(1 - x^(2*k))))^2, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 11 2017 *)

Formula

G.f.: Product_{k>0} ((1 - x^(6*k))/((1 - x^k)*(1 - x^(2*k))*(1 - x^(3*k))))^2.
a(n) ~ 5^(5/4) * exp(2*Pi*sqrt(5*n)/3) / (72 * sqrt(3) * n^(7/4)). - Vaclav Kotesovec, Oct 11 2017

A293386 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. Product_{i>0} 1/(1 + Sum_{j=1..k} j*x^(j*i))^2.

Original entry on oeis.org

1, 1, 0, 1, -2, 0, 1, -2, 1, 0, 1, -2, -3, -2, 0, 1, -2, -3, 10, 4, 0, 1, -2, -3, 4, -4, -4, 0, 1, -2, -3, 4, 14, -20, 5, 0, 1, -2, -3, 4, 6, -8, 41, -6, 0, 1, -2, -3, 4, 6, 16, -46, 2, 9, 0, 1, -2, -3, 4, 6, 6, -30, 14, -111, -12, 0, 1, -2, -3, 4, 6, 6, 0, -58
Offset: 0

Views

Author

Seiichi Manyama, Oct 07 2017

Keywords

Examples

			Square array begins:
   1,  1,   1,  1,  1, ...
   0, -2,  -2, -2, -2, ...
   0,  1,  -3, -3, -3, ...
   0, -2,  10,  4,  4, ...
   0,  4,  -4, 14,  6, ...
   0, -4, -20, -8, 16, ...
		

Crossrefs

Columns k=0..1 give A000007, A022597.
Rows n=0 gives A000012.
Main diagonal gives A252650.
Product_{i>0} (1 + Sum_{j=1..k} j*x^(j*i))^m: this sequence (m=-2), A290217 (m=-1), A290216 (m=1), A293377 (m=2).
Showing 1-3 of 3 results.