A179468 - OEIS

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A179468

G.f. satisfies: A(x) = exp( Sum_{n>=1} A(sigma(n)*x^n)*x^n/n ).

1, 1, 2, 4, 10, 22, 62, 146, 420, 1050, 3124, 7956, 23957, 62486, 192129, 509457, 1560782, 4196095, 13066095, 35437076, 109838408, 301261013, 944939968, 2605796828, 8124857765, 22597326279, 71095025143, 198583977503

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Table of n, a(n) for n=0..27.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 10*x^4 + 22*x^5 + 62*x^6 +...

log(A(x)) = A(x)*x + A(3*x^2)*x^2/2 + A(4*x^3)*x^3/3 + A(7*x^4)*x^4/4 +...

PROG

(PARI)

{a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, subst(A, x, sigma(m)*x^m+x*O(x^n))*x^m/m))); polcoeff(A, n)}

CROSSREFS