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

A362760

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

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =7a(5) =16a(6) =84a(7) =403a(8) =3028a(9) =25431a(10) =250377a(11) =2726361a(12) =32622807a(13) =423310642a(14) =5921052187a(15) =88759485250

External references