OFFSET
0,5
FORMULA
a(n) = Sum_{k=3..n} 3^(n-k) * binomial(n,k) * |Stirling1(k,3)|.
PROG
(PARI) a(n) = sum(k=3, n, 3^(n-k)*binomial(n, k)*abs(stirling(k, 3, 1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 19 2025
STATUS
approved
