circle packing algorithm

Hi, 

I am looking to create a geometry consisting of hexagonally packed spheres along the interior walls of a closed cylinder (ie. along end walls and azimuthal walls). It does not have to be optimal, so where the end walls meet the azimuthal wall there is some leniency, but there can be no overlap of the spheres. I am a relatively new AutoCAD user, so I am wondering if

a) there is code already generated which will hexagonally pack circles/spheres within a surface, or 

b) if AutoCAD is the best program to use for something so mathematically technical. If not, does anyone have a suggestion as to which program will be able to accomplish this project?

I really appreciate any advice...

Thank you,

Kelly

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