A158108 L.g.f.: exp(Sum_{n>=1} a(n)*x^n/n) = 1 + x*exp(Sum_{n>=1} sigma(n)*a(n)*x^n/n).

1, 1, 4, 21, 186, 1366, 19433, 180541, 3083809, 44941136, 895695901, 11809732422, 359749783368, 5445775854961, 140573612743254, 3607678852423757, 119036988031104164, 2273841364845589333, 93765800142590570954

Offset

1,3

Links

Table of n, a(n) for n=1..19.

Formula

L.g.f.: exp(Sum_{n>=1} a(n)*x^n/n) = 1 + x*G(x) where G(x) = g.f. of A158107.

Prog

(PARI) {a(n)=local(A=x+x^2); if(n==0, 1, for(i=1, n-1, A=log(1+x*exp(sum(m=1, n, sigma(m)*x^m*polcoeff(A+x*O(x^m), m) )+x*O(x^n)))); n*polcoeff(A, n))}

Crossrefs

Cf. A158107.

Sequence in context: A231434 A221370 A224500 * A158258 A065527 A267988

Adjacent sequences: A158105 A158106 A158107 * A158109 A158110 A158111

Keyword

nonn

Author

Paul D. Hanna, Mar 28 2009

Status

approved