OFFSET
0,2
FORMULA
a(n) = -4 * (n-1)! + 8 * |Stirling1(n,2)| for n > 0.
PROG
(PARI) a(n) = if(n==0, 1, -4*(n-1)!+8*abs(stirling(n, 2, 1)));
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Sep 05 2024
STATUS
approved