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A373872
a(n) = Sum_{k=1..n} (-1)^(n-k) * k! * k^(n-3) * Stirling2(n,k).
3
0, 1, 0, 1, 15, 391, 16275, 999391, 85314915, 9682617631, 1411532175075, 257220473522431, 57317980108103715, 15338554965273810271, 4855172557420679314275, 1794588990417909081447871, 766066194581899382513514915, 374061220058388896558805473311
OFFSET
0,5
FORMULA
E.g.f.: Sum_{k>=1} (1 - exp(-k*x))^k / k^3.
Sum_{k>=0} a(k+2) * x^k/k! = Sum_{k>=0} k * (1 - exp(-k*x))^k.
PROG
(PARI) a(n) = sum(k=1, n, (-1)^(n-k)*k!*k^(n-3)*stirling(n, k, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 20 2024
STATUS
approved