July 2002
Intermediate to advanced
320 pages
8h 15m
English
C. P. Wormell [Wor] improves on Willans’s formulas by avoiding both trigonometric functions and the floor function. Wormell’s formula can in principle be evaluated by a simple computer program that uses only integer arithmetic. The derivation does not use Wilson’s theorem. Wormell starts with, for x ≥ 2,
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Thus, the number of primes ≤ m is given by
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because the summand is the predicate “x is prime.”
Observe that, for n ≥ 1, a ≥ 0,
Repeating a trick above, the predicate a < n is
Because
we have, upon factoring constants ...
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