Proper divisors vs prime factors about extra-bigint HOT 4 CLOSED

I can have primeFactors() return [factor_i, ...], and primeFactorEntries() return [[factor_i, power_i]]. I am assuming small arrays are optimized (for primeFactorEntries()). Any ideas why this might be a good/bad choice?

There could be several optimizations (such as skipping multiples of 3), but for the time being it makes sense to have a working implementation and tests. How do you find proper divisors from the rime factors? I guess it would be based on combinations.

Thanks @skaunov for your sharing.

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@skaunov Please see primeFactors() and primeExponentials().

• primeFactors() returns an array of prime factors (only).
• primeExponentials() return an array of pairs of prime factors and their exponents.

I use an array of pairs as it can be easily converted to a Map, and allows binary search.

Also added minPrimeFactor() and maxPrimeFactor().

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Looks like an improvement to me! Thank you. =)

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