A177448 G.f.: Sum_{n>=0} a(n)*x^n/(1+x)^(2*n^2) = 1+x.

1, 1, 2, 13, 166, 3324, 92718, 3354712, 150206430, 8050991676, 504049958320, 36172232930282, 2931474921768206, 265078092222575572, 26480336590135734816, 2898139377307388441520, 345055687960080723910286

Offset

0,3

Links

Table of n, a(n) for n=0..16.

Formula

a(n) = number of subpartitions of the partition [0,1,6,15,28,...,2(n-1)^2-(n-1)] for n>0 with a(0)=1. See A115728 for the definition of subpartitions.

Example

1+x = 1 + 1*x/(1+x)^2 + 2*x^2/(1+x)^8 + 13*x^3/(1+x)^18 + 166*x^4/(1+x)^32 + 3324*x^5/(1+x)^50 + 92718*x^6/(1+x)^72 +...

Prog

(PARI) {a(n)=local(F=1/(1+x+x*O(x^n))); polcoeff(1+x-sum(k=0, n-1, a(k)*x^k*F^(2*k^2)), n)}

Crossrefs

Cf. A177447, A177449, A177450.

Sequence in context: A090643 A132521 A360601 * A258224 A351021 A078363

Adjacent sequences: A177445 A177446 A177447 * A177449 A177450 A177451

Keyword

nonn

Author

Paul D. Hanna, May 09 2010

Status

approved