a(n) = 2^n + prime(n).

Terms

a(0) =4a(1) =7a(2) =13a(3) =23a(4) =43a(5) =77a(6) =145a(7) =275a(8) =535a(9) =1053a(10) =2079a(11) =4133a(12) =8233a(13) =16427a(14) =32815a(15) =65589a(16) =131131a(17) =262205a(18) =524355a(19) =1048647a(20) =2097225a(21) =4194383a(22) =8388691a(23) =16777305a(24) =33554529a(25) =67108965a(26) =134217831a(27) =268435563a(28) =536871021a(29) =1073741937