a(n) = prime(7n-1).

Terms

a(0) =13a(1) =41a(2) =71a(3) =103a(4) =139a(5) =179a(6) =223a(7) =257a(8) =293a(9) =347a(10) =383a(11) =431a(12) =463a(13) =509a(14) =569a(15) =607a(16) =647a(17) =691a(18) =743a(19) =797a(20) =839a(21) =883a(22) =941a(23) =991a(24) =1033a(25) =1087a(26) =1123a(27) =1187a(28) =1231a(29) =1289