Josuke and Complete Graph

Josuke received a huge undirected weighted complete$$$^\dagger$$$ graph $$$G$$$ as a gift from his grandfather. The graph contains $$$10^{18}$$$ vertices. The peculiarity of the gift is that the weight of the edge between the different vertices $$$u$$$ and $$$v$$$ is equal to $$$\gcd(u, v)^\ddagger$$$. Josuke decided to experiment and make a new graph $$$G'$$$. To do this, he chooses two integers $$$l \le r$$$ and deletes all vertices except such vertices $$$v$$$ that $$$l \le v \le r$$$, and also deletes all the edges except between the remaining vertices.

Now Josuke is wondering how many different weights are there in $$$G'$$$. Since their count turned out to be huge, he asks for your help.

$$$^\dagger$$$ A complete graph is a simple undirected graph in which every pair of distinct vertices is adjacent.

$$$^\ddagger$$$ $$$\gcd(x, y)$$$ denotes the greatest common divisor (GCD) of the numbers $$$x$$$ and $$$y$$$.