NAJPWG  Playing with GCD
Tanmoy recently learn about Euclid gcd algorithm. This algorithm looks like:
gcd(a, b): if (b == 0): return a return gcd(b, a % b)
Now he want to find out how many pair (x, y) can be possible in range N, which gcd is greater than 1. Here pair (x, y) and (y, x) consider as same pair. 1<=x, y<=N.
He can find out it small number easily but for a large number its really hard to find out. Now he needs your help. Write a programme that find out number of such pair.
Input
Input start with an integer number T ( ≤ 10^5), which is number of test cases.
Each test case contain a integer N (1 ≤ N ≤ 10^5).
Output
For each case, print case number and desired answer
Sample
Input: 2 3 4 Output: Case 1: 2 Case 2: 4
hide comments
awhfahim:
20220611 22:06:04
little bit tricky.... Last edit: 20220611 22:06:37 

ayu_031201:
20220107 09:01:34
observation on phi + prefix sum :) 

mursaleen:
20200805 08:00:52
About output format : There's no blank line before the first test case. And there's a space between "Case" and the case number, and between the colon (':') and the answer. 

dhruv788:
20200716 18:16:04
Beware of the output format , There is no next line before the test case 1


thiefthief:
20191005 07:10:46
??????? Last edit: 20191005 07:40:34 

selfcoder24:
20190713 17:29:24
Concept of Phi and observation. Be extra sure on the output format :) 

immim:
20181222 06:03:14
Phi Sieve + Cumulative sum.....See output format. :) 

m2do:
20180312 19:36:09
Euler Totient + DP <3 

itachi_2016:
20180102 15:27:33
Very easy ! 

chetan4060:
20180101 11:45:39
ac in second go:)

Added by:  Najmuzzaman 
Date:  20141031 
Time limit:  0.5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 