A170810 Number of permutations of 1..n with all differences of elements separated by distances 1 through 4 being respectively unique.

1, 2, 4, 12, 40, 116, 200, 444, 760, 2160, 4872, 11932, 29252, 71708, 191356, 536908, 1607592, 5184252, 17331516, 61597568, 228854684, 891958912

Offset

1,2

Comments

(Empirical) Equals A008404 for n<=2m+2, where m is the maximum difference separation 4.

Links

Table of n, a(n) for n=1..22.

Crossrefs

Sequence in context: A170813 A170812 A170811 * A170809 A170808 A366579

Adjacent sequences: A170807 A170808 A170809 * A170811 A170812 A170813

Keyword

nonn

Author

R. H. Hardin Dec 02 2009

Status

approved