OFFSET
1,1
LINKS
Mikk Heidemaa, Table of n, a(n) for n = 1..7
MATHEMATICA
Select[Table[(10^(n + 2) + 107)/9, {n, 10^3}], PrimeQ] (* or *)
Select[FromDigits /@ Rest@ NestList["1" <> # &, "23", 10^3], PrimeQ]
PROG
(PARI) is(n)=isprime((10^(n+2) + 107)/9) \\ Anders Hellström, Nov 27 2015
(Magma) [a: n in [1..250] | IsPrime(a) where a is (10^(n+2) + 107) div 9 ]; // Vincenzo Librandi, Nov 29 2015
CROSSREFS
KEYWORD
nonn,base,hard,more
AUTHOR
Mikk Heidemaa, Nov 17 2015
STATUS
approved