Ménage numbers: a(0) = 1, a(1) = -1, and for n >= 2, a(n) = number of permutations s of [0, ..., n-1] such that s(i) != i and s(i) != i+1 (mod n) for all i.
A000179
Ménage numbers: a(0) = 1, a(1) = -1, and for n >= 2, a(n) = number of permutations s of [0, ..., n-1] such that s(i) != i and s(i) != i+1 (mod n) for all i.
Terms
- a(0) =1a(1) =-1a(2) =0a(3) =1a(4) =2a(5) =13a(6) =80a(7) =579a(8) =4738a(9) =43387a(10) =439792a(11) =4890741a(12) =59216642a(13) =775596313a(14) =10927434464a(15) =164806435783
External references
- oeis: A000179