Number of nonroot nodes of outdegree 2 in all hex trees with n edges.

A126185

Number of nonroot nodes of outdegree 2 in all hex trees with n edges.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =3a(4) =29a(5) =198a(6) =1180a(7) =6570a(8) =35196a(9) =184128a(10) =948516a(11) =4835295a(12) =24469005a(13) =123174810a(14) =617662890a(15) =3088403955a(16) =15409111025a(17) =76755126600a(18) =381848749720

External references