a(n) = 2^n - A108411(n).

Terms

a(0) =0a(1) =1a(2) =1a(3) =5a(4) =7a(5) =23a(6) =37a(7) =101a(8) =175a(9) =431a(10) =781a(11) =1805a(12) =3367a(13) =7463a(14) =14197a(15) =30581a(16) =58975a(17) =124511a(18) =242461a(19) =504605a(20) =989527a(21) =2038103a(22) =4017157a(23) =8211461a(24) =16245775a(25) =33022991a(26) =65514541a(27) =132623405a(28) =263652487a(29) =532087943