OFFSET
0,6
FORMULA
E.g.f. A(x) satisfies A(x) = 1 - x * A(x)^2 * log(1 - (x * A(x))^4).
a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} (2*n-4*k)! * |Stirling1(k,n-4*k)|/k!.
PROG
(PARI) a(n) = sum(k=0, n\4, (2*n-4*k)!*abs(stirling(k, n-4*k, 1))/k!)/(n+1);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 21 2026
STATUS
approved
