A177297 - OEIS

%I #6 Jan 18 2016 18:33:11

%S 1,1,20,1680,369600,168168000,137225088000,182509367040000,

%T 369398958888960000,510778379991559680000

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

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

%Y Cf. A014606.

%K nonn

%O 0,3

%A _R. H. Hardin_, May 06 2010