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A371175
Expansion of e.g.f. (1 + x^2 + x^3)^x.
0
1, 0, 0, 6, 24, -60, -360, 4200, 40320, -211680, -4384800, 11309760, 738460800, 1816214400, -148445256960, -1475025552000, 32459383756800, 764727970406400, -5456626240665600, -382783823399577600, -1390652097778944000, 189934744994362368000
OFFSET
0,4
FORMULA
a(n) = n! * Sum_{j=0..floor(n/2)} Sum_{k=0..j} binomial(j,n-2*j-k) * Stirling1(j,k)/j!.
PROG
(PARI) a(n) = n!*sum(j=0, n\2, sum(k=0, j, binomial(j, n-2*j-k)*stirling(j, k, 1)/j!));
CROSSREFS
Cf. A371159.
Sequence in context: A265393 A292908 A293017 * A292889 A366546 A272951
KEYWORD
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AUTHOR
Seiichi Manyama, Mar 14 2024
STATUS
approved