Number of leaf nodes in a binary tree.

Terms

a(0) =2a(1) =3a(2) =5a(3) =7a(4) =11a(5) =16a(6) =24a(7) =36a(8) =54a(9) =81a(10) =122a(11) =183a(12) =274a(13) =411a(14) =617a(15) =925a(16) =1388a(17) =2082a(18) =3123a(19) =4684a(20) =7026a(21) =10539a(22) =15809a(23) =23713a(24) =35570a(25) =53355a(26) =80032a(27) =120048a(28) =180072a(29) =270108