Number of primitive (period n) periodic palindromic structures using exactly three different symbols.

A056519

Number of primitive (period n) periodic palindromic structures using exactly three different symbols.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =5a(6) =6a(7) =18a(8) =25a(9) =63a(10) =90a(11) =202a(12) =301a(13) =650a(14) =965a(15) =2016a(16) =3025a(17) =6220a(18) =9330a(19) =18970a(20) =28495a(21) =57650a(22) =86526a(23) =174210a(24) =261624a(25) =525693a(26) =788945a(27) =1582462a(28) =2375101a(29) =4759482

External references