Basis for code in A075937.

Terms

a(0) =127a(1) =1927a(2) =6553a(3) =10922a(4) =19252a(5) =98731a(6) =164529a(7) =295709a(8) =559292a(9) =1083662a(10) =2132519a(11) =4230034a(12) =125829127a(13) =427819033a(14) =713031722a(15) =1258291252a(16) =6467616811a(17) =10779361329a(18) =19377684509a(19) =36649828412a(20) =71017955342