A177296 Number of permutations of 3 copies of 1..n with all adjacent differences <= 6 in absolute value.

1, 1, 20, 1680, 369600, 168168000, 137225088000, 182509367040000, 156952841101056000, 96333779412718848000

Offset

0,3

Comments

a(n) = (3n)!/6^n for n<=7.

Links

Table of n, a(n) for n=0..9.

Crossrefs

Cf. A014606.

Sequence in context: A177616 A177295 A177635 * A177297 A014606 A330196

Adjacent sequences: A177293 A177294 A177295 * A177297 A177298 A177299

Keyword

nonn

Author

R. H. Hardin, May 06 2010

Status

approved