Numbers k such that (856*10^k - 1) / 9 is prime.

Terms

a(0) =2a(1) =3a(2) =5a(3) =8a(4) =9a(5) =15a(6) =20a(7) =24a(8) =41a(9) =63a(10) =66a(11) =99a(12) =281a(13) =300a(14) =462a(15) =686a(16) =726a(17) =1196a(18) =1574a(19) =2543a(20) =3023a(21) =5322a(22) =12161a(23) =13677a(24) =33797a(25) =137633