Numbers n such that 2*10^n - 7 is prime.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =16a(6) =21a(7) =28a(8) =48a(9) =82a(10) =122a(11) =130a(12) =282a(13) =304a(14) =4602a(15) =12984a(16) =13614a(17) =42762a(18) =90597a(19) =109928a(20) =158242