OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 3 followed by the digits 59 is prime (see Example section).
a(34) > 3*10^5.
LINKS
Makoto Kamada, Factorization of near-repdigit-related numbers.
Makoto Kamada, Search for 63w59.
EXAMPLE
3 is in this sequence because (19*10^3 + 77) / 3 = 6359 is prime.
Initial terms and associated primes:
a(1) = 1, 89;
a(2) = 2, 659
a(3) = 3, 6359;
a(4) = 5, 633359;
a(5) = 6, 6333359, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(19*10^# + 77) / 3] &]
PROG
(PARI) is(n)=ispseudoprime((19*10^n + 77)/3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Aug 31 2016
EXTENSIONS
a(29)-a(31) from Robert Price, May 28 2019
a(32)-a(33) from Robert Price, Jun 01 2023
STATUS
approved