In Project Euler 47, why is 2^2 considered a prime number distinct from 2? -

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how code reflect that? should have consider number 4 prime?

project euler: problem 47

the first 3 consecutive numbers have 3 distinct prime factors are:

644 = 2² × 7 × 23
645 = 3 × 5 × 43
646 = 2 × 17 × 19.

if factorize 644 2 × 2 × 7 × 23. 644 has 4 prime factors, 3 distinct prime factors.


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