UVa 10820 - Send a Table

10820 - Send a Table

 * http://acm.uva.es/p/v108/10820.html

Summary
Given a number $$N$$, find the cumulative sum of the number of numbers relatively prime to $$\leq N$$.

Explanation
Use Euler's Phi function, and cache the answers.

$$ f(n) = f(n-1) + 2 \phi(n)

Input
100 1 2 3 4 5 10 20 30 200 300 1000 2000 3000 50000 0

Output
6087 1 3 7 11 19 63 255 555 24463 54795 608383 2433175 5472375 1519848527

$$