Number of identity bracelets of n beads of 2 colors.

Terms

a(0) =2a(1) =1a(2) =0a(3) =0a(4) =0a(5) =1a(6) =2a(7) =6a(8) =14a(9) =30a(10) =62a(11) =127a(12) =252a(13) =493a(14) =968a(15) =1860a(16) =3600a(17) =6902a(18) =13286a(19) =25446a(20) =48914a(21) =93775a(22) =180314a(23) =346420a(24) =666996a(25) =1284318a(26) =2477328a(27) =4781007a(28) =9240012a(29) =17870709