Number of primitive (aperiodic) reversible strings with n beads using a maximum of three different colors.

A056314

Number of primitive (aperiodic) reversible strings with n beads using a maximum of three different colors.

Terms

    a(0) =3a(1) =3a(2) =15a(3) =39a(4) =132a(5) =357a(6) =1131a(7) =3276a(8) =9945a(9) =29508a(10) =88935a(11) =265668a(12) =798252a(13) =2391441a(14) =7177584a(15) =21523320a(16) =64579920a(17) =193709763a(18) =581160255a(19) =1743392040a(20) =5230264026a(21) =15690529437a(22) =47071855131a(23) =141214764600

External references