Maximal Coprime Subset

Define $Co (n)$ to be the maximal possible sum of a set of mutually co-prime elements from ${1, 2, \dots, n}$ .
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 $Co (200000)$ .

Write-up coming later

The complete problem is available here. An approach, code, and answer will be added later.