Number of n-bead necklace structures using exactly four different colored beads.

A056297

Number of 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) =221a(8) =866a(9) =3437a(10) =13250a(11) =51075a(12) =194810a(13) =742651a(14) =2823766a(15) =10738881a(16) =40843370a(17) =155494751a(18) =592614050a(19) =2261625725a(20) =8643289534a(21) =33080920607a(22) =126797503250a(23) =486710971595

External references