Sum of Digits

[axn]

Originally Posted by Jayder

Whoa, how did you do that?

Wrote my own code. Does a range of about 2^31 per second (on 1 core of a 3GHz i5)

[Jayder]

Are you willing to share it? With mudkip's code (and a few adjustments) I only got up to 9*10^12.

[axn]

Here you go:

There is source and 64-bit executable. While in theory a 32-bit executable can be compiled, it'll lose some of the performance since the code uses 64-bit integers heavily (even where it doesn't need it :-))

This is command line executable which takes two parameters, a start and end value. It then checks all numbers (2^16*start <= n < 2^16*end). To avoid missing any numbers, the end value of one range should be used as the start value of next range.

The program writes all candidates that survive at least base 64 to a file. Also the best so far are written to screen.

EDIT:- I have already checked everything < 34e9*2^16

[davar55]

So from these:

base = 50 @ n = 13655684
base = 98 @ n = 188893618365750

the OP answer is 50 -> 13655684, 100 -> 188893618365750.

Great work !