OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..403
FORMULA
a(n) = Sum_{k=0..n} binomial(n,k)^2 * k! * A000522(n-k).
a(n) = Sum_{k=0..n} binomial(n,k) * k! * 2^k * A000262(n-k).
a(n) ~ n! * exp(1) * 2^n. - Vaclav Kotesovec, Jan 26 2020
MAPLE
b:= proc(n) b(n):= `if`(n<0, 0, 1+n*b(n-1)) end:
a:= n-> n!*add(binomial(n, k)*b(k)/k!, k=0..n):
seq(a(n), n=0..23); # Alois P. Heinz, Jan 24 2020
MATHEMATICA
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 24 2020
STATUS
approved