Number of necklaces with 7 black beads and n-7 white beads.

Terms

a(0) =1a(1) =1a(2) =4a(3) =12a(4) =30a(5) =66a(6) =132a(7) =246a(8) =429a(9) =715a(10) =1144a(11) =1768a(12) =2652a(13) =3876a(14) =5538a(15) =7752a(16) =10659a(17) =14421a(18) =19228a(19) =25300a(20) =32890a(21) =42288a(22) =53820a(23) =67860a(24) =84825a(25) =105183a(26) =129456a(27) =158224a(28) =192130a(29) =231880