Number of primitive (aperiodic) reversible strings with n beads using exactly two different colors.

A056318

Number of primitive (aperiodic) reversible strings with n beads using exactly two different colors.

Terms

    a(0) =0a(1) =1a(2) =4a(3) =7a(4) =18a(5) =29a(6) =70a(7) =126a(8) =266a(9) =507a(10) =1054a(11) =2037a(12) =4158a(13) =8183a(14) =16488a(15) =32760a(16) =65790a(17) =131026a(18) =262654a(19) =524265a(20) =1049524a(21) =2097119a(22) =4196350a(23) =8388450a(24) =16781292a(25) =33554367a(26) =67116784a(27) =134217657a(28) =268451838

External references