Given a number N we have to find the summation of all possible LCM(i,j) where i <= j <= N.
Constraints: N<=10^6 and total test case <= 10^5
Problem Link : Light OJ 1375
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Use the explanation of this problem as a hint: http://blog.forthright48.com/2015/08/spoj-lcmsum-lcm-sum.html
Thank you so much :) Sam vai already wrote about this didn't notice earlier :P
You're welcome :P
Can you please provide the solution for this? The above link seems dead
https://forthright48.com/spoj-lcmsum-lcm-sum/
Here you go