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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). 2
1, 1, 4, 21, 186, 1366, 19433, 180541, 3083809, 44941136, 895695901, 11809732422, 359749783368, 5445775854961, 140573612743254, 3607678852423757, 119036988031104164, 2273841364845589333, 93765800142590570954 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
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
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 28 2009
STATUS
approved

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Last modified March 1 08:46 EST 2024. Contains 370430 sequences. (Running on oeis4.)