Number of conjugacy classes of subgroups of index n in free group of rank 3.

A057006

Number of conjugacy classes of subgroups of index n in free group of rank 3.

Terms

    a(0) =1a(1) =7a(2) =41a(3) =604a(4) =13753a(5) =504243a(6) =24824785a(7) =1598346352a(8) =129958211233

External references