A174077 Number of permutations of length n with no consecutive triples i,i+2,i+4 (mod n) or i,i-2,i-4 (mod n).
1, 1, 2, 0, 24, 80, 504, 3794, 31616, 290970, 2973600, 33311520, 405781344, 5342413414, 75612197528, 1144942063230, 18471128518656, 316309310084728, 5730646943736936
Offset: 0
Examples
As an example, (0,4,1,2,3) is counted by a(5), but (0,4,1,3,2) is not because it has the progression 4,1,3.
Extensions
Definition corrected by Isaac Lambert, Mar 15 2010
a(0)-a(4) and a(10)-a(18) from Alois P. Heinz, Apr 15 2021