Concatenations C1 and C2 are both prime (see the comment lines).

Terms

a(0) =36a(1) =74a(2) =104a(3) =132a(4) =188a(5) =222a(6) =224a(7) =305a(8) =317a(9) =344a(10) =367a(11) =368a(12) =389a(13) =457a(14) =458a(15) =475a(16) =540a(17) =572a(18) =584a(19) =608a(20) =631a(21) =676a(22) =682a(23) =689a(24) =697a(25) =738a(26) =756a(27) =760a(28) =781a(29) =797