Number of primitive (aperiodic) word structures of length n which contain exactly two different symbols.

A056278

Number of primitive (aperiodic) word structures of length n which contain exactly two different symbols.

Terms

    a(0) =0a(1) =1a(2) =3a(3) =6a(4) =15a(5) =27a(6) =63a(7) =120a(8) =252a(9) =495a(10) =1023a(11) =2010a(12) =4095a(13) =8127a(14) =16365a(15) =32640a(16) =65535a(17) =130788a(18) =262143a(19) =523770a(20) =1048509a(21) =2096127a(22) =4194303a(23) =8386440a(24) =16777200a(25) =33550335a(26) =67108608a(27) =134209530a(28) =268435455a(29) =536854005

External references