%I #6 Oct 31 2013 12:17:34
%S 1,3,11,39,43,151,171,683,2255,2359,2731,9399,10923,43691,140911,
%T 149943,174763,549791,599479,699051,2796203,8727391,8965359,9588151,
%U 11184811,38350263,44739243,139090655,178956971,549687103,572942063,613576119
%N Numbers of the form (2^(i*j)-1)/((2^i-1)*(2^j-1)) where gcd(i,j) = 1.
%D C. L. Chen, R. T. Chien and C. K. Liu, On the binary representation form of certain integers, SIAM J. Appl. Math. 26 (1974), 283-293.
%t t = {1}; Do[a = (2^(i*j) - 1)/((2^i - 1)*(2^j - 1)); If[ GCD[i, j] == 1 && 1 < a < 10^9, AppendTo[t, a]], {i, 31}, {j, i - 1}]; Sort@t (* _Robert G. Wilson v_ *)
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Dec 30 2005
%E More terms from _Robert G. Wilson v_, Dec 31 2005