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%I #5 Mar 30 2012 17:34:14
%S 4,12,36,64,72,104,144,180,216,240,276,324,396,420,468,480,504,600,
%T 648,672
%N Mersenne-like sequence factors of complex imaginary square type 2*Prime[m]*n-1.
%F a(n) =if (2^n-1)/(2*n*Prime[m]-1)=Integer then n
%t digits=700 a=Delete[Union[Flatten[Table[If[ IntegerQ[(2^n-1)/(2*n*Prime[m]-1)]==True, n, 0], {n, 1, digits}, {m, 1, digits}]]], 1]
%K nonn,uned
%O 1,1
%A _Roger L. Bagula_, Jul 06 2004