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A275323
Numbers k such that (19*10^k + 161)/9 is prime.
0
2, 3, 5, 6, 8, 18, 36, 59, 80, 162, 197, 200, 405, 432, 930, 1065, 1496, 1716, 3213, 5712, 6303, 7466, 14150, 23685, 54608, 59766
OFFSET
1,1
COMMENTS
For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 1 followed by the digits 29 is prime (see Example section).
a(27) > 10^5.
EXAMPLE
5 is in this sequence because (19*10^5 + 161)/9 = 211129 is prime.
Initial terms and associated primes:
a(1) = 2, 229;
a(2) = 3, 2129;
a(3) = 5, 211129;
a(4) = 6, 2111129;
a(5) = 8, 211111129, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(19*10^# + 161)/9] &]
PROG
(PARI) is(n)=ispseudoprime((19*10^n+161)/9) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,more
AUTHOR
Robert Price, Jul 23 2016
STATUS
approved