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A351796
a(n) = n! * Sum_{k=0..n} (-k * (n-k))^k/k!.
1
1, 1, 0, 6, 36, -1240, 36810, -743568, -4441640, 2126086272, -201265464330, 13670088101120, -512174277963612, -50655591400627200, 16935777106057251442, -2936123018591228282880, 368896773292405165345200, -22278163772113766968557568
OFFSET
0,4
MATHEMATICA
a[n_] := n!*(1 + Sum[(-k*(n - k))^k/k!, {k, 1, n}]); Array[a, 18, 0] (* Amiram Eldar, Feb 19 2022 *)
PROG
(PARI) a(n) = n!*sum(k=0, n, (-k*(n-k))^k/k!);
CROSSREFS
Sequence in context: A268161 A082027 A203106 * A069031 A061234 A377973
KEYWORD
sign
AUTHOR
Seiichi Manyama, Feb 19 2022
STATUS
approved