Creating a circular matrix with one input

[DPaul]

Original problem statement was to start from left upper.

I read that the printing must start at the left upper.
(Only my calculations start in the middle )
Anyway, considering the keen intrest of TS, i branched out
to do a 3D spiral, using a device called "cube:bit", that
is available in various formats. Nice multi-colored effect :-)
Doing that, i found a different way of programming it, which
might take me back to the 2D print problem.
Keeps one busy.

Paul