A193375 E.g.f.: A(x) = exp( Sum_{n>=1} x^(n*(n+1)/2) ).

1, 1, 1, 7, 25, 61, 1201, 7771, 30577, 514585, 8089921, 63701551, 832599241, 14055894997, 137066892145, 3084240161731, 70859008063201, 849408115312561, 15997591979202817, 358582896987674455, 6017079190150763641, 209473179919282488301

Offset: 0

Author

Paul D. Hanna, Jul 24 2011

Keywords

• nonn

Examples

			E.g.f.: A(x) = 1 + x + x^2/2! + 7*x^3/3! + 25*x^4/4! + 61*x^5/5! +...
where
log(A(x)) = x + x^3 + x^6 + x^10 + x^15 + x^21 +...
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..448

Crossrefs

Cf. A010054, A193374, A205800.

Programs

PARI

{a(n)=n!*polcoeff(exp(sum(m=1,sqrtint(2*n+1),x^(m*(m+1)/2)+x*O(x^n))),n)}