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%I #19 Jul 24 2024 07:41:21
%S 27,35,69,331,589,807,1641,1801,2057,2411,4443,4889,4999,5975,11935,
%T 43715
%N Numbers k such that (2^31-1)*(6^k) - 1 is prime.
%C a(15) > 9500. - _Jinyuan Wang_, Mar 19 2020
%t With[{c=2^31-1},Select[Range[2500],PrimeQ[c 6^#-1]&]] (* _Harvey P. Dale_, Oct 22 2011 *)
%o (PARI) is(n)=ispseudoprime((2^31-1)*(6^n)-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,more
%O 1,1
%A _Pierre CAMI_, Oct 14 2004
%E a(11)-a(14) from _Jinyuan Wang_, Mar 19 2020
%E a(15) from _Michael S. Branicky_, Apr 21 2023
%E a(16) from _Michael S. Branicky_, Jul 23 2024