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

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =4a(6) =6a(7) =9a(8) =14a(9) =21a(10) =33a(11) =54a(12) =89a(13) =142a(14) =222a(15) =350a(16) =554a(17) =883a(18) =1406a(19) =2225a(20) =3511a(21) =5539a(22) =8768a(23) =13977a(24) =22417a(25) =36143a(26) =58483a(27) =94818a(28) =153716a(29) =248699