When we look at a graph that
shows only primes, like Figure 1, the leftfacing
curves are much more pronounced than the
rightfacing curves. However, when we look
at a graph that shows all the integers,
like Figure 3,
the leftfacing and rightfacing curves
are equally salient. The main reason for
this seems to be that on the left side,
primes can occur only in curves with odd
offsets. On the right side, primes can occur
in curves with both odd and even offsets.
It would be interesting to investigate empirically
whether equal quantities of primes occur
on both sides.
The number spiral is closely
related to the Ulam prime spiral, shown
in Figure 2:
