Number of permutations that are n-2 "block reversals" away from 12...n.

A007973

Number of permutations that are n-2 "block reversals" away from 12...n.

Terms

    a(0) =1a(1) =3a(2) =15a(3) =55a(4) =184a(5) =648a(6) =2111a(7) =6352a(8) =17337a(9) =42878a(10) =102050a(11) =239756a(12) =562728

External references