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A219231 G.f. satisfies: A(x) = exp( Sum_{n>=1} x^n/n * Product_{k>=1} 1/(1 - x^(n*k)*A(x^n)^k) ). 4
1, 1, 2, 5, 15, 47, 160, 554, 1987, 7243, 26873, 100930, 383412, 1469673, 5679033, 22095308, 86489211, 340360513, 1345814572, 5344184197, 21303295069, 85216434084, 341960332173, 1376212103798, 5553269024152, 22463340663474, 91071265881382, 369996643180885, 1506118767637576 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Compare to the dual g.f. G(x) of A218551:

G(x) = exp( Sum_{n>=1} x^n/n * Product_{k>=1} 1/(1 - x^(n*k)*G(x^k)^n) ).

LINKS

Table of n, a(n) for n=0..28.

EXAMPLE

G.f.: A(x) = 1 + x + 2*x^2 + 5*x^3 + 15*x^4 + 47*x^5 + 160*x^6 + 554*x^7 +...

where

log(A(x)) = x/(1*(1-x*A(x))*(1-x^2*A(x)^2)*(1-x^3*A(x)^3)*...) +

x^2/(2*(1-x^2*A(x^2))*(1-x^4*A(x^2)^2)*(1-x^6*A(x^2)^3)*...) +

x^3/(3*(1-x^3*A(x^3))*(1-x^6*A(x^3)^2)*(1-x^9*A(x^3)^3)*...) +

x^4/(4*(1-x^4*A(x^4))*(1-x^8*A(x^4)^2)*(1-x^12*A(x^4)^3)*...) +...

Explicitly,

log(A(x)) = x + 3*x^2/2 + 10*x^3/3 + 39*x^4/4 + 146*x^5/5 + 594*x^6/6 + 2346*x^7/7 + 9543*x^8/8 + 38710*x^9/9 + 158448*x^10/10 +...

PROG

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

for(n=0, 30, print1(a(n), ", "))

CROSSREFS

Cf. A218551, A219230, A219229, A219232, A218153.

Sequence in context: A013560 A192053 A149923 * A149924 A149925 A149926

Adjacent sequences:  A219228 A219229 A219230 * A219232 A219233 A219234

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Nov 16 2012

STATUS

approved

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Last modified October 22 22:22 EDT 2020. Contains 337962 sequences. (Running on oeis4.)