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.

A294953 Expansion of Product_{k>=1} (1 - k^(2*k)*x^k)^k.

Original entry on oeis.org

1, -1, -32, -2155, -259701, -48496253, -13001952944, -4732375549802, -2246504006429898, -1348407213767476321, -998562531571744073815, -894380298523142455736017, -953030939828900988652689704, -1191547999931410291515116161158
Offset: 0

Views

Author

Seiichi Manyama, Nov 12 2017

Keywords

Comments

This sequence is obtained from the generalized Euler transform in A266964 by taking f(n) = -n, g(n) = n^(2*n).

Crossrefs

Column k=2 of A294808.

Programs

  • PARI
    N=20; x='x+O('x^N); Vec(prod(k=1, N, (1-k^(2*k)*x^k)^k))

Formula

a(0) = 1 and a(n) = -(1/n) * Sum_{k=1..n} A294955(k)*a(n-k) for n > 0.

A294950 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 in powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 9, 6, 1, 1, 33, 90, 13, 1, 1, 129, 2220, 1162, 24, 1, 1, 513, 59178, 265132, 17435, 48, 1, 1, 2049, 1594836, 67180330, 49163241, 310193, 86, 1, 1, 8193, 43048770, 17181660628, 152662629227, 13121450895, 6286826, 160
Offset: 0

Views

Author

Seiichi Manyama, Nov 12 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, ...
   13,  1162,   265132,     67180330,     17181660628, ...
   24, 17435, 49163241, 152662629227, 476855156157129, ...
		

Crossrefs

Columns k=0..2 give A000219, A294813, A294954.
Rows n=0+1, 2 give A000012, A087289.

Formula

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

A294955 a(n) = Sum_{d|n} d^(2*n+2).

Original entry on oeis.org

1, 65, 6562, 1049601, 244140626, 78368963450, 33232930569602, 18014467229220865, 12157665462543713203, 10000002384185795209930, 9849732675807611094711842, 11447546167874515876354097130, 15502932802662396215269535105522
Offset: 1

Views

Author

Seiichi Manyama, Nov 12 2017

Keywords

Crossrefs

Programs

  • PARI
    {a(n) = sigma(n, 2*n+2)}
    
  • PARI
    N=20; x='x+O('x^N); Vec(sum(k=1, N, k^(2*k+2)*x^k/(1-(k^2*x)^k)))

Formula

G.f.: Sum_{k>0} k^(2*k+2)*x^k/(1-(k^2*x)^k).
Showing 1-3 of 3 results.