Numbers k such that k * 20^k - 1 is prime.

Terms

a(0) =1a(1) =18a(2) =44a(3) =60a(4) =80a(5) =123a(6) =429a(7) =1166a(8) =2065a(9) =8774a(10) =35340a(11) =42968a(12) =50312a(13) =210129