%I A015910
%S A015910 0,0,2,0,2,4,2,0,8,4,2,4,2,4,8,0,2,10,2,16,8,4,2,16,7,4,26,16,2,4,2,
%T A015910 0,8,4,18,28,2,4,8,16,2,22,2,16,17,4,2,16,30,24,8,16,2,28,43,32,8,4,
%U A015910 2,16,2,4,8,0,32,64,2,16,8,44,2,64,2,4,68,16,18,64,2,16,80,4,2,64
%N A015910 2^n (mod n).
%C A015910 a(0) could equally well be taken to be 1.
%C A015910 Certain residues do not appear below exponent n < 10000. E.g. 1,3,5,6,
               9,.. Also, some [r=12,13,14,15,16] arise first at large exponents 
               [3763,95,1010,481,20]. Do all values eventually appear? - Labos E. 
               (labos(AT)ana.sote.hu), Jan 03 2002
%C A015910 Known solutions to 2^n = 3 (mod n) are given in A050259.
%C A015910 For n an odd prime the sequence is equal to 2. - Paolo P. Lava (ppl(AT)spl.at), 
               Feb 09 2007
%D A015910 R. K. Guy, Unsolved Problems in Number Theory, F10.
%H A015910 T. D. Noe, <a href="b015910.txt">Table of n, a(n) for n=1..10000</a>
%H A015910 Albert Frank, <a href="http://www.paulcooijmans.com/oth/intcont2003.html">
               International Contest Of Logical Sequences</a>, 2002 - 2003. Item 
               4
%H A015910 Albert Frank, <a href="http://www.paulcooijmans.com/oth/intcont2003ans.html">
               Solutions of International Contest Of Logical Sequences</a>, 2002 
               - 2003.
%H A015910 Peter L. Montgomery, <a href="http://www.cs.ucla.edu/~klinger/newno.html">
               65-digit solution</a>.
%p A015910 a:=n->2^n mod(n): seq(a(n), n=1..84); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Feb 15 2008
%p A015910 seq(irem(2^n,n),n=1..84); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Apr 20 2008
%t A015910 Table[PowerMod[2, n, n], {n, 85} ]
%Y A015910 Cf. A036236, A015911.
%Y A015910 Sequence in context: A144182 A037036 A055947 this_sequence A164993 A023987 
               A021498
%Y A015910 Adjacent sequences: A015907 A015908 A015909 this_sequence A015911 A015912 
               A015913
%K A015910 nonn
%O A015910 1,3
%A A015910 Robert G. Wilson v (rgwv(AT)rgwv.com)