SPOJ.com - Problem LCMSUM

LCMSUM - LCM Sum

#number-theory

Given n, calculate the sum LCM(1,n) + LCM(2,n) + .. + LCM(n,n), where LCM(i,n) denotes the Least Common Multiple of the integers i and n.

The first line contains T the number of test cases. Each of the next T lines contain an integer n.

Output T lines, one for each test case, containing the required sum.

Sample Input:
3
1
2
5

Sample Output:
1
4
55

1 <= T <= 300000
1 <= n <= 1000000

< Previous 1 2 3 Next >

	DK...: 2018-08-30 18:43:29 i got TL using pragma's, but AC without them...
	uvshuvo: 2018-06-29 01:30:42 Learned a lot about phi function nice math logic Thanks. Last edit: 2018-06-29 01:34:23
	crackeree: 2018-05-03 14:49:26 how alien i m. everyone is getting TLE .. and i m getting WA..
	chetan4060: 2018-01-01 09:51:18 nice math used:)
	epsilonalpha: 2017-12-14 07:37:25 It's a must do NT problem. AC in one go, however I had already read the solution so it doesn't count I guess. :P
	shub120798: 2017-09-27 08:51:33 really nice prblm.. pre-compute each and every thing to avoid tle;..
	rohit9934: 2017-06-30 13:09:54 I have got so many TLE's in this Some points before attempting. prefer Pre-computation guys otherwise TLE GCD will not work even the straight forward formula Don't use endl in c++ use "\n" otherwise TLE Dont use cin cout , use printf, scanf otherwise TLE. Must do ,you will learn a lot. Last edit: 2017-06-30 13:10:30
	da_201501181: 2017-04-02 13:54:53 Learned a lot..!! Nice Question..!!
	rohan_c_23: 2016-10-13 13:33:03 Wonderful mathematics!!
	square1001: 2016-07-23 13:36:06 I suggest this problem: LCM Rush(Japanese). But problem statement is simple. You're given N and K. Calculate LCM(1,K) + LCM(2,K) + LCM(3,K) + ... + LCM(N,K). http://abc020.contest.atcoder.jp/tasks/abc020_d#

Added by:	Varun Jalan
Date:	2010-01-24
Time limit:	0.527s
Source limit:	50000B
Memory limit:	1536MB
Cluster:	Cube (Intel G860)
Languages:	All except: PERL6
Resource:	own problem used for Codechef Snackdown Onsite