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Numbers b such that b^(2^n) + 3 is prime for n from 0 to 4.
2

%I #6 May 06 2013 00:48:18

%S 2564954,4505138,6319754,10004666,13410068,28358686,31079126,31331314,

%T 37983154,40470296,43452004,58717498,66643660,67991588,77422568,

%U 77995658,79257766,98229376,101553298,123965218,125464136,126241688,130818598,130838170,131305474

%N Numbers b such that b^(2^n) + 3 is prime for n from 0 to 4.

%C Generalized Fermat numbers of the form b^(2^n) + k with k = 3 here.

%t Select[Prime@Range[3, 10^6]-3, PrimeQ[#^2 + 3] && PrimeQ[#^4 + 3] && PrimeQ[#^8 + 3] && PrimeQ[#^16 + 3] &] (* _Giovanni Resta_, May 05 2013 *)

%Y Cf. A070694

%K nonn

%O 1,1

%A _Robin Garcia_, May 05 2013

%E Missing terms a(2) and a(5) and a(12)-a(25) from _Giovanni Resta_, May 05 2013