A378155 G.f. A(x) satisfies A(x) = ( 1 + x * A(x)^(2/3) * (1 + A(x)^(2/3)) )^3.
1, 6, 48, 452, 4680, 51504, 591312, 7002864, 84926304, 1049402944, 13165069824, 167239042176, 2146912312064, 27808372643328, 362981425115904, 4769884412086016, 63050983340533248, 837805424714425344, 11184489029495865344, 149935005483457542144, 2017560365768892739584
Offset: 0
Keywords
Programs
-
PARI
a(n, r=3, t=2, u=2) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));
Formula
G.f.: B(x)^3 where B(x) is the g.f. of A219534.
a(n) = 3 * Sum_{k=0..n} binomial(n,k) * binomial(2*n+2*k+3,n)/(2*n+2*k+3).