A358604 a(n) = Sum_{k=0..floor(n/3)} (-1)^k * (n-2*k)!/(n-3*k)!.
1, 1, 1, 0, -1, -2, -1, 2, 7, 8, -1, -26, -49, -28, 103, 314, 359, -344, -2113, -3682, -161, 14684, 36791, 25762, -100297, -373456, -472241, 587846, 3877487, 7149988, -1111801, -40808566, -103472249, -56751688, 424662623, 1490284654, 1674543359, -4121143444
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..1000
Programs
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PARI
a(n) = sum(k=0, n\3, (-1)^k*(n-2*k)!/(n-3*k)!);
Formula
a(n) = (2 * a(n-1) - n * a(n-3) + 1)/3 for n > 2.