A165960 Number of permutations of length n without modular 3-sequences.

1, 1, 2, 3, 20, 100, 612, 4389, 35688, 325395, 3288490, 36489992, 441093864, 5770007009, 81213878830, 1223895060315, 19662509071056, 335472890422812, 6057979285535388, 115434096553014565, 2314691409652237700, 48723117262650147387, 1074208020519710570054

Offset: 0

Author

Isaac Lambert, Oct 01 2009

Keywords

• nonn

Comments

Modular 3-sequences are of the following form: i,i+1,i+2, where arithmetic is modulo n.

Examples

			For n=3 the a(3) = 3 solutions are (0,2,1), (1,0,2) and (2,1,0).
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..450

Crossrefs

Cf. A002628, A165961, A165962.

Formula

a(n) = n * A165961(n).

Extensions

a(0)-a(2) and a(15)-a(22) from Alois P. Heinz, Apr 14 2021