OFFSET
0,3
FORMULA
E.g.f. A(x) satisfies A(x) = ( 1 - x*A(x)*log(1 - x*A(x)) )^2.
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A371229.
a(n) = 2 * n! * (2*n+1)! * Sum_{k=0..floor(n/2)} |Stirling1(n-k,k)|/( (n-k)! * (2*n-k+2)! ).
PROG
(PARI) a(n) = 2*n!*(2*n+1)!*sum(k=0, n\2, abs(stirling(n-k, k, 1))/((n-k)!*(2*n-k+2)!));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 27 2024
STATUS
approved