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%I #3 Mar 31 2012 12:38:27
%S 2,1,1,4,256,4194304,4503599627370496,
%T 20769187434139310514121985316880384,
%U 1766847064778384329583297500742918515827483896875618958121606201292619776
%N Integers of the form a(n)=2^n/n^2.
%e 2^8/8^2=4, .. n :: 1,2,4,8,16,32,64,128,256,512,..
%t lst={};Do[i=2^n/n^2;If[IntegerQ[i],AppendTo[lst,i]],{n,6!}];lst
%o (PARI) a(n)=2^(2^(n-1))/(2^(2*n-2))
%Y Cf. A007758
%K nonn,easy
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Sep 22 2009
%E Program by _Charles R Greathouse IV_, Oct 12 2009
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