OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} 2^k * (k+1)! * |Stirling1(n,k)|.
a(0) = 1; a(n) = 2*Sum_{k=1..n} (k/n + 1) * (k-1)! * binomial(n,k) * a(n-k).
PROG
(PARI) a(n) = sum(k=0, n, 2^k*(k+1)!*abs(stirling(n, k, 1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 19 2023
STATUS
approved