Search: id:A052007
Results 1-1 of 1 results found.

%I A052007
%S A052007 1,3,5,9,15,39,75,81,89,317,701,735,1311,1881,3201,3225,11795,88071,
%T A052007 204129,678561
%N A052007 Numbers n such that 2^n + n is prime.
%C A052007 Terms >= 701 are currently only strongpseudoprime.
%C A052007 If n=1 (mod 6) or n=2 (mod 6) then 3 divides 2^n+n. Thus for n > 1, a(n)!=1 
               (mod 6) and a(n)!=2 (mod 6). The next term is greater than 20000 
               with the next prime having more than 6020 digits.
%H A052007 Henri Lifchitz, Renaud Lifchitz, <a href="http://www.primenumbers.net/
               prptop/searchform.php?form=2%5En%2Bn">PRP Top Records.</a> 2^n+n.
%H A052007 <a href="http://groups.yahoo.com/group/primeform/">Primeform:</a> User 
               group for PFGW & PrimeForm programs.
%e A052007 2^39 + 39 = 549755813927 is prime.
%t A052007 Do[ If[ PrimeQ[ 2^n + n ], Print[ n ] ], {n, 0, 7000} ]
%t A052007 v={1}; Do[If[Mod[n, 2]*(Mod[n, 6]-1)!= 0&&PrimeQ[2^n+n], v=Append[v, 
               n]; Print[v]], {n, 2, 20000}]
%Y A052007 Cf. A006127, A048744.
%Y A052007 Sequence in context: A017913 A140428 A027154 this_sequence A117480 A018260 
               A023656
%Y A052007 Adjacent sequences: A052004 A052005 A052006 this_sequence A052008 A052009 
               A052010
%K A052007 nonn,nice,hard
%O A052007 1,2
%A A052007 G. L. Honaker, Jr. (honak3r(AT)gmail.com) and Patrick De Geest (pdg(AT)worldofnumbers.com), 
               Nov 15 1999.
%E A052007 11795 from Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Aug 21 
               2003
%E A052007 88071 from Hugo Pfoertner (hugo(AT)pfoertner.org), Dec 26 2004
%E A052007 More terms from Henri Lifchitz submitted by Ray Chandler (rayjchandler(AT)sbcglobal.net), 
               Mar 02 2007

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