OFFSET
0,4
FORMULA
a(0) = 0, a(1) = 1; a(n+1) = Sum_{k=1..n-1} 2^(n-k) * (k-1)! * binomial(n,k) * a(n-k).
PROG
(PARI) a_vector(n) = my(v=vector(n)); v[1]=1; for(i=1, n-1, v[i+1]=sum(j=1, i-1, 2^(i-j)*(j-1)!*binomial(i, j)*v[i-j])); concat(0, v);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 25 2022
STATUS
approved