Number of legal Go positions on a 1 X n board (for which 3^n is a trivial upper bound).

Terms

a(0) =1a(1) =5a(2) =15a(3) =41a(4) =113a(5) =313a(6) =867a(7) =2401a(8) =6649a(9) =18413a(10) =50991a(11) =141209a(12) =391049a(13) =1082929a(14) =2998947a(15) =8304961a(16) =22998865a(17) =63690581a(18) =176377839a(19) =488441801a(20) =1352638145a(21) =3745850473a(22) =10373355075a(23) =28726852897a(24) =79553054089a(25) =220305664445a(26) =610090792143