B-trees of order 5 with n labeled leaves.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =7a(7) =11a(8) =20a(9) =36a(10) =67a(11) =121a(12) =215a(13) =377a(14) =657a(15) =1154a(16) =2045a(17) =3666a(18) =6628a(19) =12063a(20) =22079a(21) =40642a(22) =75264a(23) =140191a(24) =262457a(25) =493297a(26) =929703a(27) =1754941a(28) =3314509a(29) =6258052