A174078 Number of circular permutations of length n with no consecutive triples i,i+2,i+4 or i,i-2,i-4.

20, 100, 600, 4244, 34264, 311424, 3143912, 34833964, 420917638, 5513592091, 77715460917

Offset: 5

Author

Isaac Lambert, Mar 10 2010

Keywords

• nonn

Comments

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

Examples

			For n=5 there are (5-1)!-a(5)=4 circular permutations with i,i+2,i+4 or i,i-2,i-4 triples. They are (0,2,4,1,3), (0,2,4,3,1), (0,1,3,4,2), and (0,3,1,4,2).
		

Crossrefs

Cf. A165964, A174076, A174077, A174079.

Extensions

a(10)-a(15) from Donovan Johnson, Sep 24 2010