%I A161818
%S A161818 3,7,5,31,9,127,17,73,33,2047,65,8191,129,1057,257,131071,513,524287,
%T A161818 1025,16513,2049,8388607,4097,1082401,8193,262657,16385,536870911,32769,
%U A161818 2147483647,65537,4196353,131073,270549121,262145,137438953471,524289
%N A161818 If b(n) = the largest proper divisor of n, then a(n) = (2^n -1)/(2^b(n) 
               -1).
%e A161818 a(6)=(2^6-1)/(2^3-1)=63/7=9. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), 
               Jun 26 2009]
%p A161818 with(numtheory): a := proc (n) options operator, arrow: (2^n-1)/(2^divisors(n)[tau(n)-1]-1) 
               end proc: seq(a(n), n = 2 .. 40); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), 
               Jun 26 2009]
%Y A161818 A032742
%Y A161818 Sequence in context: A064078 A048857 A005420 this_sequence A161509 A108974 
               A106853
%Y A161818 Adjacent sequences: A161815 A161816 A161817 this_sequence A161819 A161820 
               A161821
%K A161818 nonn
%O A161818 2,1
%A A161818 Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jun 20 2009
%E A161818 Extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 26 2009