Number of non-complete compositions of n.

Terms

a(0) =0a(1) =1a(2) =1a(3) =4a(4) =8a(5) =14a(6) =31a(7) =63a(8) =129a(9) =248a(10) =509a(11) =1011a(12) =2044a(13) =4089a(14) =8167a(15) =16360a(16) =32725a(17) =65482a(18) =131017a(19) =262176a(20) =524167a(21) =1048678a(22) =2096985a(23) =4194358a(24) =8387802a(25) =16776408a(26) =33550943a(27) =67101615a(28) =134199983a(29) =268399122