Numbers k such that the concatenation of 2^k - 1 and 2^(k - 1) - 1 is prime.

Terms

a(0) =2a(1) =3a(2) =4a(3) =7a(4) =8a(5) =12a(6) =19a(7) =22a(8) =36a(9) =46a(10) =51a(11) =67a(12) =79a(13) =215a(14) =359a(15) =394a(16) =451a(17) =1323a(18) =2131a(19) =3336a(20) =3371a(21) =6231a(22) =19179a(23) =39699a(24) =51456a(25) =56238a(26) =69660a(27) =75894a(28) =79798a(29) =92020