Number of primitive (aperiodic) reversible string structures with n beads using a maximum of two different colors.

A056331

Number of primitive (aperiodic) reversible string structures with n beads using a maximum of two different colors.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =16a(6) =35a(7) =66a(8) =133a(9) =261a(10) =527a(11) =1032a(12) =2079a(13) =4123a(14) =8244a(15) =16440a(16) =32895a(17) =65639a(18) =131327a(19) =262380a(20) =524762a(21) =1049071a(22) =2098175a(23) =4195230a(24) =8390646a(25) =16779231a(26) =33558392a(27) =67112892a(28) =134225919a(29) =268443306

External references