OFFSET
1,1
COMMENTS
For k > 1, numbers k such that the digits 88 followed by k-1 occurrences of the digit 3 followed by the digit 9 is prime (see Example section).
a(33) > 2*10^5.
LINKS
Makoto Kamada, Factorization of near-repdigit-related numbers.
Makoto Kamada, Search for 883w9.
EXAMPLE
3 is in this sequence because (265*10^3 + 17)/3 = 88339 is prime.
Initial terms and associated primes:
a(1) = 2, 8839;
a(2) = 3, 88339;
a(3) = 4, 883339;
a(4) = 10, 883333333339;
a(5) = 35, 8833333333333333333333333333333333339, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(265*10^# + 17)/3] &]
PROG
(PARI) is(n)=ispseudoprime((265*10^n + 17)/3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, May 01 2016
EXTENSIONS
a(32) from Robert Price, Mar 21 2020
STATUS
approved