Number of primitive (aperiodic) palindromes using exactly two different symbols.

Terms

a(0) =0a(1) =0a(2) =2a(3) =2a(4) =6a(5) =4a(6) =14a(7) =12a(8) =28a(9) =24a(10) =62a(11) =54a(12) =126a(13) =112a(14) =246a(15) =240a(16) =510a(17) =476a(18) =1022a(19) =990a(20) =2030a(21) =1984a(22) =4094a(23) =4020a(24) =8184a(25) =8064a(26) =16352a(27) =16254a(28) =32766a(29) =32484