Number of cycles with entries of the same parity in all fixed-point-free involutions of {1,2,...,2n}.
A161122
Number of cycles with entries of the same parity in all fixed-point-free involutions of {1,2,...,2n}.
Terms
- a(0) =0a(1) =0a(2) =2a(3) =18a(4) =180a(5) =2100a(6) =28350a(7) =436590a(8) =7567560a(9) =145945800a(10) =3101348250a(11) =72020198250
External references
- oeis: A161122