Project Euler Forum

I am having difficulty counting the number of iterations (it may be just a fence post problem).

Could anyone confirm that it takes takes:
19 iterations to produce 2 ^ 2
36980 iterations to produce 2 ^ 29
73886466 iterations to produce 2 ^ 379

Thanks.

I haven't solved it yet. I have a basic algorithm that can generate the primes but it would take a lot of time to find the answer being asked. In your case, the first one is correct. But the remaining two are off by 1.

Edit: I can now confirm my above statement after solving this problem.

Did you have any difficulty in getting the program to run in under a minute?

Is an unsigned 32 (or 64) bit integer enough to store the answer?

32: no. 64: yes.

There seem to exist two valid versions. Version A takes 707 steps to find 2^7, Version B takes 710 steps.

On which of those does the correct solution rely?

I vote for 710...

Is that vote because you've already solved this? Or just a guess...

Solved, but you never know...

Apparently it's the slow branch then. Thanks