First of all, that is not the formula for a sum of digits. It is the formula to calculate the sum of the first N positive integers.
Secondly, and more importantly, I can't see where you have...
Type: Posts; User: Zaphod_b
First of all, that is not the formula for a sum of digits. It is the formula to calculate the sum of the first N positive integers.
Secondly, and more importantly, I can't see where you have...