Number of directed cycles of B-trees of order 3 with n labeled leaves.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =8a(6) =15a(7) =24a(8) =46a(9) =82a(10) =157a(11) =293a(12) =576a(13) =1095a(14) =2138a(15) =4156a(16) =8162a(17) =16019a(18) =31675a(19) =62608a(20) =124341a(21) =247224a(22) =493067a(23) =984905a(24) =1971970a(25) =3953749a(26) =7941397a(27) =15971775a(28) =32168510a(29) =64866564