A177294 Number of permutations of 3 copies of 1..n with all adjacent differences <= 4 in absolute value.

1, 1, 20, 1680, 369600, 168168000, 41494252800, 6923871998400, 983114244363720, 139528504017728552

Offset: 0

Author

R. H. Hardin, May 06 2010

Keywords

• nonn

Comments

a(n) = (3n)!/6^n for n<=5.

Crossrefs

Cf. A014606.