// perfect num calculation is 2^(p-1)*(2^p - 1)// source: https://oeis.org/A000396letgetPerfectp=pown2L(p-1)*(pown2Lp-1L)
Usage
// prime calculation is out of scope for this problem// (and this few can be looked up easily)// so I simply list them here.letmersenneExponents=[1;2;3;5;7;13;17;19;31]List.mapgetPerfectmersenneExponents|>printfn"%A"// [1L; 6L; 28L; 496L; 8128L; 33550336L; 8589869056L; 137438691328L; 2305843008139952128L]
This runs in 0.35ms or ~3500 ticks in Release mode (after a JIT prerun). It basically turns the problem around to be just a matter of inputting Mersenne Exponents. Not many are needed before overflowing traditional memory structures like int64.
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F#, ridiculously short/fast solution
Usage
This runs in 0.35ms or ~3500 ticks in Release mode (after a JIT prerun). It basically turns the problem around to be just a matter of inputting Mersenne Exponents. Not many are needed before overflowing traditional memory structures like
int64.