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A171554
Numbers k such that 1 + 9*10^k + 100^k is prime.
4
0, 1, 5, 71, 311
OFFSET
1,3
COMMENTS
No more terms up to k = 7200.
No more terms up to k = 27200. - Michael S. Branicky, Jun 30 2024
MATHEMATICA
Select[Range[0, 320], PrimeQ[1+9 10^#+100^#]&] (* Harvey P. Dale, Nov 23 2023 *)
PROG
(PARI) is(n)=ispseudoprime(1+9*10^n+100^n) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Jason Earls, Dec 11 2009
STATUS
approved