a(n) = Sum_{i=0..n-1} 2^i*prime(n-i).

Terms

a(0) =2a(1) =7a(2) =19a(3) =45a(4) =101a(5) =215a(6) =447a(7) =913a(8) =1849a(9) =3727a(10) =7485a(11) =15007a(12) =30055a(13) =60153a(14) =120353a(15) =240759a(16) =481577a(17) =963215a(18) =1926497a(19) =3853065a(20) =7706203a(21) =15412485a(22) =30825053a(23) =61650195a(24) =123300487a(25) =246601075a(26) =493202253a(27) =986404613a(28) =1972809335a(29) =3945618783