Binary-ternary Wedderburn-Etherington numbers.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =4a(5) =9a(6) =23a(7) =58a(8) =156a(9) =426a(10) =1194a(11) =3393a(12) =9802a(13) =28601a(14) =84347a(15) =250732a(16) =750908a(17) =2262817a(18) =6857386a(19) =20882889a(20) =63877262a(21) =196162762a(22) =604567254a(23) =1869318719a(24) =5797113028a(25) =18026873112a(26) =56197262814a(27) =175594836698a(28) =549839459963