The Natural Numbers #12

This work is defined by the iteration.
Apart from the texture detail there is no randomisation.
Interaction: key 'f' to toggle the foreground figure.
key 't' to toggle text based information.
Lucky refers to Euler's lucky number set.
Semiprime does not include square semiprimes.
The foreground figure is coded up to 1000000, after which only the background will be drawn.