Save some work on PE 44.
Brute-force PE 45.
PE 45: every hexagonal number is also triangular.
PE 45: find pentagonals by solving a quadratic.
PE 45: don't generate 73,000 extra hexagon numbers.
PE 44: use fast test for pentagonality.
PE 46 - Goldbach's other conjecture.
PE 46: less awful prime test. 3x speedup.
Don't require the whole Racket runtime for utils.