Numbers n such that 5*10^n-1 is prime.

Terms

a(0) =2a(1) =3a(2) =4a(3) =6a(4) =14a(5) =54a(6) =210a(7) =390a(8) =594a(9) =3460a(10) =5028a(11) =5219a(12) =5332a(13) =8072a(14) =15796a(15) =16131a(16) =21456a(17) =29282a(18) =78790a(19) =85142a(20) =179972a(21) =211029a(22) =445773a(23) =464843a(24) =511056