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A377347
E.g.f. satisfies A(x) = 1 + (exp(x*A(x)^2) - 1)/A(x)^2.
2
1, 1, 1, 7, 41, 391, 4509, 62847, 1038001, 19580071, 418681877, 9973993855, 262293996777, 7545559829991, 235715629493005, 7946944965054271, 287592204406672481, 11120005819664145895, 457514133092462477253, 19957535405566629526335, 920056233384401619083545
OFFSET
0,4
FORMULA
a(n) = Sum_{k=0..floor((2*n+1)/3)} (2*n-2*k)!/(2*n-3*k+1)! * Stirling2(n,k).
PROG
(PARI) a(n) = sum(k=0, (2*n+1)\3, (2*n-2*k)!/(2*n-3*k+1)!*stirling(n, k, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 26 2024
STATUS
approved