%I A127102
%S A127102 1,7,889,2359,299593,2033143,13549249,42931441,100170217,310935751,
%T A127102 685169191
%N A127102 Numbers n such that n^2 divides 8^n-1.
%C A127102 a(n) is a subset of A014949(n) = {1, 7, 49, 343, 889, 2359, 2401, 6223, 
               16513, ...} Numbers n such that n divides 8^n-1.
%C A127102 a(5) = 299593 = (8^7-1)/7 is a repunit in base 8, 1111111( base 8). Note 
               that the first 5 listed terms of a(n) are the terms of a finite sequence 
               {1, 7, 49, 127, 337, 889, 2359, 6223, 16513, 42799, 299593, 2097151} 
               = A003530(n) Divisors of 2^21 - 1.
%t A127102 Select[Range[20000], IntegerQ[(PowerMod[8, #, #^2 ]-1)/#^2 ]&]
%Y A127102 Cf. A127100, A127101, A127103, A127104, A127105, A127106, A127107, A127092. 
               Cf. A014949 = numbers n such that n divides 8^n-1.
%Y A127102 Cf. A003530.
%Y A127102 Sequence in context: A047788 A087350 A093171 this_sequence A038808 A068728 
               A028990
%Y A127102 Adjacent sequences: A127099 A127100 A127101 this_sequence A127103 A127104 
               A127105
%K A127102 hard,more,nonn
%O A127102 1,2
%A A127102 Alexander Adamchuk (alex(AT)kolmogorov.com), Jan 05 2007, Jan 07 2007
%E A127102 More terms from Ryan Propper (rpropper(AT)stanford.edu), Jan 05 2007