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A272523
Numbers k such that (265*10^k + 17)/3 is prime.
0
2, 3, 4, 10, 35, 60, 65, 72, 87, 218, 226, 326, 365, 461, 611, 1244, 1566, 4839, 4913, 5396, 7020, 8410, 9714, 10362, 11405, 21695, 25240, 56076, 56588, 74579, 81990, 114736
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.
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
KEYWORD
nonn,more
AUTHOR
Robert Price, May 01 2016
EXTENSIONS
a(32) from Robert Price, Mar 21 2020
STATUS
approved