10927434464domain: NAppears in sequencesMénage 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.at n=14A000179Same as A000179, except that a(0) = 2.at n=14A102761A variant of A000179 and A102761.at n=14A335700