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URL: https://oeis.org/A197038

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A197038
Numbers k such that (2^k + 3^k)/97 is prime.
0
12, 412, 436, 916
OFFSET
1,1
COMMENTS
a(5) > 10^5. - Michael S. Branicky, Apr 15 2025
EXAMPLE
a(1) = 12 => (2^12+3^12)/97 = 5521 is prime.
(2^a(2)+3^a(2))/97 has 195 digits.
(2^a(3)+3^a(3))/97 has 207 digits.
(2^a(4)+3^a(4))/97 has 436 digits.
MATHEMATICA
lst={}; Do[If[PrimeQ[(2^k+3^k)/97], AppendTo[lst, k]], {k, 1000}]; lst
Select[Range[10000], PrimeQ[(2^#+3^#)/97]&] (* Harvey P. Dale, Aug 22 2013 *)
PROG
(PARI) is(n)=ispseudoprime((2^n+3^n)/97) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A003772 A211078 A299382 * A282883 A163971 A340306
KEYWORD
nonn,hard,more
AUTHOR
Michel Lagneau, Oct 08 2011
STATUS
approved