In the last Codeforces round, one possible solution to Div 2 Problem D / Div 1 Problem B (named "Integers have Friends") used sparse table data structure to handle range GCD queries. So I posted a new video tutorial explaining what a sparse table is and how we can use it to handle range GCD queries.
After watching that tutorial, you should be able to solve / up-solve (if you did the contest and didnt solve it in contest) the Codeforces problem.
I also made a video editorial for that problem: Link to the video editorial for Integers have Friends
Hope this helps some of you.