A358611 a(n) = Sum_{k=0..floor(n/5)} (-1)^k * (n-5*k)!.
1, 1, 2, 6, 24, 119, 719, 5038, 40314, 362856, 3628681, 39916081, 478996562, 6226980486, 87177928344, 1307670739319, 20922749971919, 355686949099438, 6402367478747514, 121645013230903656, 2432900700505900681, 51090921248959468081, 1124000372090658580562
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..449
Programs
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PARI
a(n) = sum(k=0, n\5, (-1)^k*(n-5*k)!);
Formula
a(n) = n * a(n-1) - a(n-5) + n * a(n-6) for n > 5.