Number of primitive (period n) n-bead necklace structures using exactly four different colored beads.

A056305

Number of primitive (period n) n-bead necklace structures using exactly four different colored beads.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =13a(6) =50a(7) =220a(8) =866a(9) =3435a(10) =13250a(11) =51061a(12) =194810a(13) =742601a(14) =2823764a(15) =10738660a(16) =40843370a(17) =155493872a(18) =592614050a(19) =2261622287a(20) =8643289484a(21) =33080907357a(22) =126797503250a(23) =486710920300

External references