Number of permutations of n elements containing a 2-cycle.

A027616

Number of permutations of n elements containing a 2-cycle.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =3a(4) =9a(5) =45a(6) =285a(7) =1995a(8) =15855a(9) =142695a(10) =1427895a(11) =15706845a(12) =188471745a(13) =2450132685a(14) =34301992725a(15) =514529890875

External references