Number of necklaces with 9 black beads and n-9 white beads.

Terms

a(0) =1a(1) =1a(2) =5a(3) =19a(4) =55a(5) =143a(6) =335a(7) =715a(8) =1430a(9) =2704a(10) =4862a(11) =8398a(12) =14000a(13) =22610a(14) =35530a(15) =54484a(16) =81719a(17) =120175a(18) =173593a(19) =246675a(20) =345345a(21) =476913a(22) =650325a(23) =876525a(24) =1168710a(25) =1542684a(26) =2017356a(27) =2615104a(28) =3362260a(29) =4289780