OFFSET
0,5
FORMULA
a(n) = Sum_{k=3..n} 2^(n-k) * binomial(k,3) * Stirling2(n,k).
PROG
(PARI) a(n) = sum(k=3, n, 2^(n-k)*binomial(k, 3)*stirling(n, k, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 19 2025
STATUS
approved
