Some parts of this library were copied from elsewhere on the internet.  When I
first started assembling this library, I had no ambitions of publication, and as
such, I wasn't terribly concerned with attribution; consequently, some of the
proper sourcing of the copied code is lost.  The sources I can recall are:

The function siqs is derived from Stephan Kollman's repository at
https://github.com/skollmann/PyFactorise.

The Hamming number generator is modified from a recipe by Raymond Hettinger at
https://code.activestate.com/recipes/576961/.

The S1 and S2 phases of the primepi code are translated from Kim Walish's primecount package:
https://github.com/kimwalisch/primecount.

The primesum code is copied from Lucy_Hedgehog's post at https://projecteuler.net/thread=10;page=5.

The totientsum code is derived from the Project Euler #351 overview.

Part of the function sqrtmod_prime appears to be derived from https://codegolf.stackexchange.com/a/9088.
