A124381 O.g.f.: A(x) = Sum_{n>=0} x^n*Product_{k=0..n} (1 + k*(k+1)/2*x).

1, 1, 2, 5, 14, 48, 181, 772, 3620, 18511, 102869, 613584, 3926895, 26734671, 193310243, 1477081245, 11896869336, 100700815331, 893438783126, 8291513009130, 80302486087937, 810290260679230, 8502192961792190

Offset

0,3

Links

Table of n, a(n) for n=0..22.

Example

A(x) = 1 + x*(1+x) + x^2*(1+x)*(1+3x) + x^3*(1+x)*(1+3x)*(1+6x) +...

Prog

(PARI) a(n)=polcoeff(sum(k=0, n, x^k*prod(j=0, k, 1+j*(j+1)/2*x+x*O(x^n))), n)

Crossrefs

Sequence in context: A149906 A129778 A060797 * A131236 A119499 A079452

Adjacent sequences: A124378 A124379 A124380 * A124382 A124383 A124384

Keyword

nonn

Author

Paul D. Hanna, Oct 28 2006

Status

approved