OFFSET
0,3
FORMULA
a(0) = 1; a(n) = Sum_{k=1..n} 2^(n-k) * (k-1)! * binomial(n,k) * a(n-k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, 2^(i-j)*(j-1)!*binomial(i, j)*v[i-j+1])); v;
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 18 2022
STATUS
approved