Number of permutations of [n] for which the first two entries have the same parity (n>=2).
A152661
Number of permutations of [n] for which the first two entries have the same parity (n>=2).
Terms
- a(0) =0a(1) =2a(2) =8a(3) =48a(4) =288a(5) =2160a(6) =17280a(7) =161280a(8) =1612800a(9) =18144000a(10) =217728000a(11) =2874009600a(12) =40236134400a(13) =610248038400
External references
- oeis: A152661