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%I #5 Nov 21 2013 12:49:20
%S 521,11293772630057337854244300009061892827351888021,
%T 6573840876841765045097738044023218580610053625908525039752324422200521,
%U 164346021921044126127443451100580464515251340647713125993808110555013021
%N Primes of form (5^n+1)/6.
%t a={};Do[x=(5^n+1)/6;If[PrimeQ[x],AppendTo[a,x]],{n,0,12^2}];a
%t Select[(5^Range[0,200]+1)/6,PrimeQ] (* _Harvey P. Dale_, Jul 18 2011 *)
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, May 15 2008