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%I #20 Sep 08 2022 08:46:16
%S 0,2,4,6,12,18,24,42,84,300,390,780,822,2430,5508,5514,6492,12372,
%T 22680,25770,169416,174240,383544,1007838,1572882
%N Numbers n such that (2^n + 5) / 3 is prime.
%C Larger members of the sequence generate probable primes only.
%C Corresponding prime numbers are: 2, 3, 7, 23, 1367, 87383, 5592407, 1466015503703,6447604371278022265099607,.. etc.
%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=%282%5En%2B5%29%2F3&action=Search">(2^n+5)/3 PRPs</a> [PRP Top Records]
%F a(n) = 2*A261539(n).
%t Select[Range[0,10000], PrimeQ[(2^# + 5)/3] &]
%o (Magma) [n: n in [0..2000] | (2^n+5) mod 3 eq 0 and IsPrime((2^n+5) div 3)];
%o (PARI) is(n)=ispseudoprime((2^n+5)/3) \\ _Charles R Greathouse IV_, Jun 07 2016
%Y Cf. A261539.
%K nonn,more
%O 1,2
%A _Vincenzo Librandi_, May 13 2016
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