OFFSET
0,2
FORMULA
a(0) = 1; a(n) = Sum_{k=1..n} (1 + 2^k + 3^k + 4^k) * binomial(n-1,k-1) * a(n-k).
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=1, 4, exp(k*x)-1))))
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, (1+2^j+3^j+4^j)*binomial(i-1, j-1)*v[i-j+1])); v;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 01 2022
STATUS
approved