Maximal coprime subset (noch nicht übersetzt)
Problem 355
Define Co(n) to be the maximal possible sum of a set of mutually co-prime elements from {1, 2, ..., n}.
For example Co(10) is 30 and hits that maximum on the subset {1, 5, 7, 8, 9}.
You are given that Co(30) = 193 and Co(100) = 1356.
Find Co(200000).