This is an interactive visualization of the Ulam spiral.
Use the up and down buttons to "zoom" in or out. Use the left and right buttons to change the starting point. And press the "1" button to reset the starting point to its default value 1.
[Should work with recent desktop versions of Chrome or Firefox.]

Copyright (c) 2016, Prof. Dr. Edmund WeitzImpressum, Datenschutzerklärung