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A120916 G.f. satisfies: A(x) = C(2x)*A(x^3*C(2x)^4), where C(x) is the g.f. of the Catalan numbers (A000108). 3
1, 2, 8, 42, 244, 1504, 9656, 63856, 431872, 2972778, 20756036, 146627648, 1046060836, 7525452296, 54530660832, 397628393728, 2915496099136, 21481907631872, 158975372309176, 1181109256858096, 8806197969093184 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Self-convolution equals A120915, which equals column 0 of triangle A120914 (cascadence of (1+2x)^2).

LINKS

Table of n, a(n) for n=0..20.

PROG

(PARI) {a(n)=local(A=1+2*x, C=(1/x*serreverse(x/(1+4*x+4*x^2+x*O(x^n))))^(1/2)); for(i=0, n, A=C*subst(A, x, x^3*C^4 +x*O(x^n))); polcoeff(A, n, x)}

CROSSREFS

Cf. A120914, A120915, A000108.

Sequence in context: A231103 A114204 A129277 * A133417 A235350 A100327

Adjacent sequences:  A120913 A120914 A120915 * A120917 A120918 A120919

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 17 2006

STATUS

approved

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Last modified July 24 17:43 EDT 2021. Contains 346273 sequences. (Running on oeis4.)