A177297 Number of permutations of 3 copies of 1..n with all adjacent differences <= 7 in absolute value.

1, 1, 20, 1680, 369600, 168168000, 137225088000, 182509367040000, 369398958888960000, 510778379991559680000

Offset

0,3

Comments

a(n) = (3n)!/6^n for n<=8.

Links

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

Crossrefs

Cf. A014606.

Sequence in context: A177295 A177635 A177296 * A014606 A330196 A172556

Adjacent sequences: A177294 A177295 A177296 * A177298 A177299 A177300

Keyword

nonn

Author

R. H. Hardin, May 06 2010

Status

approved