OFFSET
0,2
EXAMPLE
29 (=10^1+19) and 10000000019 (=10^10+19) are primes so a(1)=19.
PROG
(PARI) okm(m, n) = {for (k=0, n, if (!isprime(10^10^k + m), return (0)); ); return (1); }
a(n) = {m = 0; while (!okm(m, n), m++); m; } \\ Michel Marcus, Mar 16 2014
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Farideh Firoozbakht, Mar 13 2014
EXTENSIONS
a(4) from Giovanni Resta, Mar 14 2014
STATUS
approved