Number of pairs of adjacent vertices of outdegree 2 in all hex trees with n edges.
A126190
Number of pairs of adjacent vertices of outdegree 2 in all hex trees with n edges.
Terms
- a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =24a(6) =190a(7) =1260a(8) =7602a(9) =43344a(10) =238308a(11) =1278360a(12) =6739590a(13) =35086392a(14) =180952200a(15) =926583840a(16) =4718481950a(17) =23923888800a(18) =120881319280a(19) =609086170080
External references
- oeis: A126190