OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).
a(31) > 2*10^5.
LINKS
Makoto Kamada, Factorization of near-repdigit-related numbers.
Makoto Kamada, Search for 50w59.
EXAMPLE
3 is in this sequence because 5*10^3 + 59 = 5059 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 3, 5059;
a(3) = 7, 50000059;
a(4) = 9, 5000000059;
a(5) = 10, 50000000059, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[5*10^# + 59] &]
PROG
(PARI) is(n)=ispseudoprime(5*10^n + 59) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Sep 05 2016
STATUS
approved