OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..450
FORMULA
a(n) = Sum_{k=0..3} k! * binomial(3,k) * |Stirling1(n,k)|.
a(0) = 1; a(n) = Sum_{k=1..n} (4 * k/n - 1) * (k-1)! * binomial(n,k) * a(n-k).
PROG
(PARI) a(n) = sum(k=0, 3, k!*binomial(3, k)*abs(stirling(n, k, 1)));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Oct 27 2024
STATUS
approved