Derangements with at least one 2-cycle.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =3a(5) =20a(6) =105a(7) =714a(8) =5845a(9) =52632a(10) =525105a(11) =5777090a(12) =69337521a(13) =901364100a(14) =12618959353a(15) =189284859750