OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 0 followed by the digits 93 is prime (see Example section).
a(35) > 10^5.
LINKS
Makoto Kamada, Factorization of near-repdigit-related numbers.
Makoto Kamada, Search for 20w93.
EXAMPLE
6 is in this sequence because 2*10^6 + 93 = 2000093 is prime.
Initial terms and associated primes:
a(1) = 1, 113;
a(2) = 2, 293;
a(3) = 6, 2000093;
a(4) = 7, 20000093;
a(5) = 8, 200000093, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[2*10^# + 93] &]
PROG
(PARI) is(n)=ispseudoprime(2*10^n+93) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Jul 31 2016
STATUS
approved