A216969 - OEIS

A216969

G.f. satisfies: A(x) = Sum_{n>=0} x^n * A(x)^(n^2) * A(-x)^(n^2).

1, 1, 1, 2, 5, 17, 51, 199, 653, 2746, 9506, 41887, 150209, 683534, 2513812, 11714529, 43913589, 208460660, 793362271, 3822998161, 14731492719, 71883765642, 279923388563, 1380780426067, 5426284435421, 27023956574169, 107069182011993, 537876237669664

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OFFSET

0,4

LINKS

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

EXAMPLE

G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 5*x^4 + 17*x^5 + 51*x^6 + 199*x^7 +...

A(x)*A(-x) = 1 + x^2 + 7*x^4 + 74*x^6 + 967*x^8 + 14251*x^10 + 227037*x^12 +...

PROG

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

for(n=0, 21, print1(a(n), ", "))

CROSSREFS

Sequence in context: A148404 A061675 A148405 * A148406 A148407 A141303

Adjacent sequences: A216966 A216967 A216968 * A216970 A216971 A216972

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 21 2012

STATUS

approved