Number of permutations of [n] having exactly two adjacent 2-cycles.
A370426
Number of permutations of [n] having exactly two adjacent 2-cycles.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =3a(6) =9a(7) =48a(8) =306a(9) =2190a(10) =17810a(11) =162480a(12) =1642635a(13) =18231465a(14) =220420179a(15) =2883693792a(16) =40592133316a(17) =611765693532
External references
- oeis: A370426