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A120918 Row sums of triangle A120914 (cascadence of (1+2x)^2). 3
1, 12, 124, 1212, 11512, 107544, 994236, 9128024, 83400856, 759387964, 6896903064, 62519804504, 565914425336, 5116780986152, 46223426993576, 417279346904792, 3764890593799336, 33953608251139560, 306100904240342268 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

FORMULA

G.f.: A(x) = H(x)*(1-x)/(1-9*x), where H(x) is the g.f. of A120915: H(x) = C(2x)^2*H(x*C(2x)^4) and C(x) is the g.f. of A000108 (Catalan).

PROG

(PARI) {a(n)=local(A, F=1+4*x+4*x^2, d=2, G=x, H=1+x, S=ceil(log(n+1)/log(d+1))); for(i=0, n, G=x*subst(F, x, G+x*O(x^n))); for(i=0, S, H=subst(H, x, x*G^d+x*O(x^n))*G/x); A=(x*H-y*subst(H, x, x*y^d +x*O(x^n)))/(x*subst(F, x, y)-y); sum(k=0, 2*n, polcoeff(polcoeff(A, n, x), k, y))}

CROSSREFS

Cf. A120914, A120915, A120916, A120917.

Sequence in context: A273586 A125424 A163147 * A262573 A039680 A332690

Adjacent sequences:  A120915 A120916 A120917 * A120919 A120920 A120921

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 17 2006

STATUS

approved

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Last modified September 20 13:56 EDT 2021. Contains 347586 sequences. (Running on oeis4.)