Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero with no three beads in a row equal.

A209338

Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero with no three beads in a row equal.

Terms

    a(0) =1a(1) =3a(2) =4a(3) =15a(4) =40a(5) =146a(6) =514a(7) =2032a(8) =8076a(9) =33310a(10) =138966a(11) =589618a(12) =2525494a(13) =10923868a(14) =47599638a(15) =208824200a(16) =921391230a(17) =4086463748a(18) =18206487792

External references