Number of Steiner triple systems (STS's) on 6n+1 or 6n+3 elements.

A001201

Number of Steiner triple systems (STS's) on 6n+1 or 6n+3 elements.

Terms

    a(0) =1a(1) =1a(2) =30a(3) =840a(4) =1197504000

External references