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A379255

G.f. A(x) satisfies A(x) = ( (1 + x*A(x))/(1 - x*A(x)^3) )^3.

1, 6, 90, 1910, 47250, 1274406, 36344906, 1077809718, 32899427106, 1026823733702, 32619190553274, 1051205539768566, 34282637873690290, 1129326395659189734, 37522172645425790634, 1255954522404101871286, 42312438228338307500610, 1433621819994034883749254

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..17.

FORMULA

G.f.: B(x)^3 where B(x) is the g.f. of A379257.

a(n) = Sum_{k=0..n} binomial(3*n+7*k+2,k) * binomial(3*n+6*k+3,n-k)/(n+2*k+1).

PROG

(PARI) a(n) = sum(k=0, n, binomial(3*n+7*k+2, k)*binomial(3*n+6*k+3, n-k)/(n+2*k+1));

CROSSREFS

Cf. A213282, A365843, A379254.