A385946 a(0) = 1; a(n) = Sum_{k=0..n-1} binomial(k+4,4) * binomial(n-1,k) * a(k) * a(n-1-k).

1, 1, 6, 106, 4176, 316696, 42104392, 9172761368, 3106804304704, 1567537597699840, 1137145604406018176, 1151190083860345401984, 1585522852991230263395584, 2906652632758146061798315776, 6959140466024956612239458880000, 21400639132670591710876896798678016

Offset: 0

Author

Seiichi Manyama, Jul 13 2025

Keywords

• nonn

Crossrefs

Cf. A000272, A156325, A385945, A385947, A385948.

Cf. A385953.

Programs

PARI

a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, i-1, binomial(j+4, 4)*binomial(i-1, j)*v[j+1]*v[i-j])); v;

Formula

E.g.f. A(x) satisfies A(x) = exp( Sum_{k=0..3} binomial(3,k) * x^(k+1)/(k+1)! * (d^k/dx^k A(x)) ), where (d^0/dx^0 A(x)) = A(x) by convention.