Number of bracelets (turn over necklaces) with n beads: 1 blue, 12 green, and r = n - 13 red.

Terms

a(0) =1a(1) =7a(2) =49a(3) =231a(4) =924a(5) =3108a(6) =9324a(7) =25236a(8) =63090a(9) =147070a(10) =323554a(11) =676270a(12) =1352540a(13) =2600612a(14) =4829708a(15) =8692788a(16) =15212379a(17) =25949469a(18) =43249115a(19) =70562765a(20) =112900424a(21) =177412664a(22) =274183208a(23) =417232088a(24) =625848132a(25) =926250780a(26) =1353751140a(27) =1955412284a(28) =2793446120a(29) =3949346840