Number of necklaces with 12 black beads and n-12 white beads.

Terms

a(0) =1a(1) =1a(2) =7a(3) =31a(4) =116a(5) =364a(6) =1038a(7) =2652a(8) =6310a(9) =14000a(10) =29414a(11) =58786a(12) =112720a(13) =208012a(14) =371516a(15) =643856a(16) =1086601a(17) =1789515a(18) =2883289a(19) =4552275a(20) =7056280a(21) =10752060a(22) =16128424a(23) =23841480a(24) =34769374a(25) =50067108a(26) =71250060a(27) =100276894a(28) =139672312