Number of subtrees of a complete binary tree.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =6a(5) =9a(6) =15a(7) =25a(8) =35a(9) =49a(10) =70a(11) =100a(12) =160a(13) =256a(14) =416a(15) =676a(16) =936a(17) =1296a(18) =1800a(19) =2500a(20) =3550a(21) =5041a(22) =7171a(23) =10201a(24) =16261a(25) =25921a(26) =41377a(27) =66049a(28) =107169a(29) =173889