OFFSET
0,3
LINKS
Winston de Greef, Table of n, a(n) for n = 0..399
FORMULA
a(n) = n! * Sum_{k=1..n} (-n+k+1)^(k-1) * binomial(n-1,n-k)/k! for n>0.
PROG
(PARI) a(n) = if(n==0, 1, n!*sum(k=1, n, (-n+k+1)^(k-1)*binomial(n-1, n-k)/k!));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Mar 01 2023
STATUS
approved