a(n) = 2*a(n-1) + 1 for a(n-1) not prime, otherwise a(n) = prime(n) - 1; with a(1) = 147.

Terms

a(0) =147a(1) =295a(2) =591a(3) =1183a(4) =2367a(5) =4735a(6) =9471a(7) =18943a(8) =37887a(9) =75775a(10) =151551a(11) =303103a(12) =606207a(13) =1212415a(14) =2424831a(15) =4849663a(16) =9699327a(17) =19398655a(18) =38797311a(19) =77594623a(20) =155189247a(21) =310378495a(22) =620756991a(23) =1241513983a(24) =2483027967a(25) =4966055935a(26) =9932111871a(27) =19864223743a(28) =39728447487a(29) =79456894975