a(n) = 2^n - A210109(n).

Terms

a(0) =2a(1) =4a(2) =8a(3) =14a(4) =25a(5) =41a(6) =74a(7) =124a(8) =222a(9) =390a(10) =706a(11) =1262a(12) =2324a(13) =4244a(14) =7869a(15) =14607a(16) =27337a(17) =51243a(18) =96665a(19) =182666a(20) =346647a(21) =659206a(22) =1257287a(23) =2402569a(24) =4601771a(25) =8828741a(26) =16969511a(27) =32665154a(28) =62972932