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Problems

GCD Extreme

GCD Extreme

Given the value of \textbf{n}, you have to find the value of \textbf{G}, where \includegraphics{https://static.e-olymp.com/content/53/53630f1afe7320d524271dd744a552787cd2966c.jpg} Here \textbf{GCD}(\textbf{i, j}) means the greatest common divisor of integer \textbf{i} and integer \textbf{j}. For those who have trouble understanding summation notation, the meaning of \textbf{G} is given in the following code: G=0;for(i=1; i < n;i++)for(j=i+1;j<=n;j++)\{ G+=GCD(i,j);\}/*Here GCD() is a function that finds the greatest common divisor of the two input numbers*/ \InputFile The input file contains at most \textbf{20000} lines of inputs. Each line contains an integer \textbf{n} (\textbf{1} < \textbf{n} < \textbf{200001}). The last line contains \textbf{n} = \textbf{0} and is not processed. \OutputFile For each line of input produce one line of output. This line contains the value of \textbf{G} for the corresponding \textbf{n}. The value of \textbf{G} will fit in a \textbf{64}-bit signed integer.
Time limit 2 seconds
Memory limit 64 MiB
Input example #1
10
100             
20000
0
Output example #1
67
13015
1153104356