Number of bracelet structures using a maximum of three different colored beads.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =9a(6) =22a(7) =40a(8) =100a(9) =225a(10) =582a(11) =1464a(12) =3960a(13) =10585a(14) =29252a(15) =80819a(16) =226530a(17) =636321a(18) =1800562a(19) =5107480a(20) =14548946a(21) =41538916a(22) =118929384a(23) =341187048a(24) =980842804a(25) =2824561089a(26) =8147557742a(27) =23536592235a(28) =68087343148a(29) =197216119545