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%I #17 Apr 11 2023 02:14:57
%S 1,2,3,5,9,25,34,36,42,52,176,262,269,283,284,289,372,392,486,596,999,
%T 1022,1097,1105,2329,2663,3037,3363,3853,5167,6305,7164,7283,8874,
%U 10974,14450,14763,15016,15320,24869,27192,35164,37595,43540
%N Numbers k such that 2^(2*k+1) + 2^k + 1 is prime.
%C a(36) > 11800. - _Jinyuan Wang_, Mar 19 2020
%e 2^3 + 2^1 + 1 = 11 prime so a(1) = 1.
%e 2^5 + 2^2 + 1 = 37 prime so a(2) = 2.
%e 2^7 + 2^3 + 1 = 137 prime so a(3) = 3.
%o (PARI) is(n)=ispseudoprime(2^(2*n+1)+2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,more
%O 1,2
%A _Pierre CAMI_, Apr 11 2005
%E a(34)-a(35) from _Jinyuan Wang_, Mar 19 2020
%E a(36)-a(41) from _Jeppe Stig Nielsen_, Jun 16 2020
%E a(42)-a(44) from _Jorge Coveiro_, Apr 10 2023