Number of conjugacy classes of subgroups of index 4 in free group of rank n.

A057010

Number of conjugacy classes of subgroups of index 4 in free group of rank n.

Terms

    a(0) =1a(1) =26a(2) =604a(3) =14120a(4) =334576a(5) =7987616a(6) =191318464a(7) =4588288640a(8) =110090411776

External references