

A174083


Number of circular permutations of length n with no consecutive triples i,i+d,i+2d (mod n) for all d.


3




OFFSET

4,1


COMMENTS

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


LINKS

Table of n, a(n) for n=4..9.


EXAMPLE

For n=5 since a(5)=0 all (51)!=24 circular permutations of length 5 have some consecutive triple i,i+d,i+2d (mod 5). For example, the permutation (0,4,2,1,3) has a triple (1,3,0) with d=2. This is clearly a special case.


CROSSREFS

Cf. A165962, A174075, A174080, A174081, A174082.
Sequence in context: A270184 A271300 A271120 * A123936 A271834 A138546
Adjacent sequences: A174080 A174081 A174082 * A174084 A174085 A174086


KEYWORD

nonn


AUTHOR

Isaac Lambert, Mar 15 2010


STATUS

approved



