Number of nonisomorphic unordered pairs of permutations of an n-set.

A362645

Number of nonisomorphic unordered pairs of permutations of an n-set.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =8a(4) =28a(5) =96a(6) =495a(7) =2919a(8) =22024a(9) =190585a(10) =1876379a(11) =20445393a(12) =244087497a(13) =3161870309a(14) =44155439841a(15) =661065427709

External references