a(n) = 2^n - A143658(n).

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =5a(5) =12a(6) =25a(7) =50a(8) =99a(9) =198a(10) =400a(11) =803a(12) =1605a(13) =3210a(14) =6422a(15) =12848a(16) =25692a(17) =51384a(18) =102784a(19) =205563a(20) =411115a(21) =822234a(22) =1644470a(23) =3288958a(24) =6577915a(25) =13155768a(26) =26311537a(27) =52623102a(28) =105246259a(29) =210492628