A379282 G.f. A(x) satisfies A(x) = 1/( (1 - x*A(x)^2) * (1 - x*A(x)) )^2.
1, 4, 34, 376, 4743, 64710, 929906, 13865206, 212509079, 3327383632, 52994140217, 855842582128, 13982509284464, 230686414552016, 3837897905208588, 64314848237403878, 1084624929809399857, 18393856772155371200, 313487249756740510907, 5366521088581773011788
Offset: 0
Keywords
Programs
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PARI
a(n) = 2*sum(k=0, n, binomial(2*n+3*k+2, k)*binomial(3*n+k+1, n-k)/(2*n+3*k+2));
Formula
G.f.: B(x)^2 where B(x) is the g.f. of A379284.
a(n) = 2 * Sum_{k=0..n} binomial(2*n+3*k+2,k) * binomial(3*n+k+1,n-k)/(2*n+3*k+2).