OFFSET
0,2
FORMULA
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A377349.
a(n) = 2 * Sum_{k=0..floor((2*n+2)/3)} (2*n-2*k+1)!/(2*n-3*k+2)! * |Stirling1(n,k)|.
PROG
(PARI) a(n) = 2*sum(k=0, (2*n+2)\3, (2*n-2*k+1)!/(2*n-3*k+2)!*abs(stirling(n, k, 1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 26 2024
STATUS
approved