A177286 Number of permutations of 2 copies of 1..n with all adjacent differences <= 5 in absolute value.

1, 1, 6, 90, 2520, 113400, 7484400, 349272000, 12629539440, 394462558980, 11673071453460, 348672825749478, 10924880404749722, 348078897908489130, 11059657083803795688, 346844915294462956440, 10705742604901078977600

Offset

0,3

Comments

a(n) = (2n)!/2^n for n<=6.

Links

Table of n, a(n) for n=0..16.

Crossrefs

Cf. A177282, A177283, A177284, A177285, A177287, A177288, A177289, A177290, A177295.

Sequence in context: A177285 A177574 A177575 * A177594 A177287 A177288

Adjacent sequences: A177283 A177284 A177285 * A177287 A177288 A177289

Keyword

nonn

Author

R. H. Hardin, May 06 2010

Extensions

a(0)=1 and a(12)-a(16) from Max Alekseyev, May 30 2025

Status

approved