A165623 Integers of the form a(n)=2^n/n^2.

2, 1, 1, 4, 256, 4194304, 4503599627370496, 20769187434139310514121985316880384, 1766847064778384329583297500742918515827483896875618958121606201292619776

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Sep 22 2009

Keywords

• nonn
• easy

Examples

			2^8/8^2=4, .. n :: 1,2,4,8,16,32,64,128,256,512,..
		

Crossrefs

Cf. A007758

Programs

Mathematica

lst={};Do[i=2^n/n^2;If[IntegerQ[i],AppendTo[lst,i]],{n,6!}];lst

PARI

a(n)=2^(2^(n-1))/(2^(2*n-2))

Extensions

Program by Charles R Greathouse IV, Oct 12 2009