Numbers k such that 42 * 10^k + 1 is prime.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =13a(5) =19a(6) =39a(7) =62a(8) =76a(9) =79a(10) =109a(11) =184a(12) =222a(13) =265a(14) =370a(15) =626a(16) =670a(17) =679a(18) =763a(19) =1950a(20) =2174a(21) =3379a(22) =7369a(23) =9087a(24) =34990a(25) =47535a(26) =97970