A174079 Number of circular permutations of length n with no consecutive triples i,i+2,i+4 (mod n) or i,i-2,i-4 (mod n).

12, 84, 494, 3696, 30574

Offset

5,1

Comments

Circular permutations are permutations whose indices are from the ring of integers modulo n.

Links

Table of n, a(n) for n=5..9.

Example

For n=5 there are (5-1)!-a(5)=12 circular permutations with triples i,i+2,i+4 (mod 5) or triples i,i-2,i-4 (mod 5). An example of one is (0,3,1,2,4) because of the progression 0,3,1 (mod 5).

Crossrefs

Cf. A078628, A174076, A174077, A174078.

Sequence in context: A004407 A054849 A000761 * A003209 A155645 A378281

Adjacent sequences: A174076 A174077 A174078 * A174080 A174081 A174082

Keyword

nonn

Author

Isaac Lambert, Mar 10 2010

Status

approved