Number of 1-sided strip polyhexes with n cells.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =15a(5) =44a(6) =121a(7) =353a(8) =1005a(9) =2919a(10) =8398a(11) =24310a(12) =70064a(13) =202225a(14) =582365a(15) =1676889a(16) =4821924a(17) =13857720a(18) =39787804