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A135870 G.f. A(x) = (1 + x*A(3x))^2. 1
1, 2, 13, 246, 13554, 2210436, 1076561037, 1570714992558, 6871883750090694, 90179738434097457084, 3550105797469080332658354, 419263945026939228053105930844, 148543119421079567735277052592081220 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Self-convolution of A135869.

LINKS

Table of n, a(n) for n=0..12.

PROG

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A, x, 3*x)^2); polcoeff(A^2, n)}

CROSSREFS

Cf. A135868, A135869.

Sequence in context: A268703 A187648 A113098 * A133067 A276744 A042677

Adjacent sequences:  A135867 A135868 A135869 * A135871 A135872 A135873

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Dec 02 2007

STATUS

approved

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Last modified September 28 01:27 EDT 2021. Contains 347698 sequences. (Running on oeis4.)