A170809 Number of permutations of 1..n with all differences of elements separated by distances 1 through 3 being respectively unique.

1, 2, 4, 12, 40, 116, 200, 444, 864, 3368, 10936, 38320, 139848, 534828, 2230464, 9802612, 46188544, 231210272, 1213437504, 6717614708, 39002297800

Offset: 1

Author

R. H. Hardin Dec 02 2009

Keywords

• nonn

Comments

(Empirical) Equals A008404 for n<=2m+2, where m is the maximum difference separation 3.