OEIS A228297: Need Help to Find Algorithm

[Gerald H]

OK, I have now stored your programme on an otherwise empty 42S (due to memory problems on the unit I customarily use) & confirm your timing for input 100 & correctness of answer.

Bravo!

Given enough computing power & sufficient energy the problem may be solved, although you could add longevity to your requirements.

However, I'll stick to the real 42S or 50g.

As for specifications, different for different models:

For 50g: Given any natural number input the correct answer is returned in a reasonable time, ie time characteristic of algorithm should be less than linear.

For 42S: Given any natural number < 5*10^11input the correct answer is returned in < 20s.