a(n) is the number of odd permutations (of an n-set) with exactly 2 fixed points.

A145223

a(n) is the number of odd permutations (of an n-set) with exactly 2 fixed points.

Terms

    a(0) =0a(1) =0a(2) =6a(3) =0a(4) =90a(5) =420a(6) =3780a(7) =33264a(8) =333900a(9) =3670920a(10) =44054010a(11) =572697840a(12) =8017775766a(13) =120266628300

External references