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

Author

R. H. Hardin, May 06 2010

Keywords

• nonn

Comments

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

Crossrefs

Cf. A014606.