| 
									
										
										
										
											2018-09-30 23:01:58 +01:00
										 |  |  | --- | 
					
						
							|  |  |  | id: 5900f4e81000cf542c50fffa | 
					
						
							|  |  |  | challengeType: 5 | 
					
						
							|  |  |  | title: 'Problem 379: Least common multiple count' | 
					
						
							|  |  |  | --- | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ## Description
 | 
					
						
							|  |  |  | <section id='description'> | 
					
						
							|  |  |  | Let f(n) be the number of couples (x,y) with x and y positive integers, x ≤ y and the least common multiple of x and y equal to n. | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 
 | 
					
						
							| 
									
										
										
										
											2018-10-08 01:01:53 +01:00
										 |  |  | Let g be the summatory function of f, i.e.: | 
					
						
							| 
									
										
										
										
											2018-09-30 23:01:58 +01:00
										 |  |  | g(n) = ∑ f(i)  for 1 ≤ i ≤ n. | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | You are given that g(106) = 37429395. | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | Find g(1012). | 
					
						
							|  |  |  | </section> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ## Instructions
 | 
					
						
							|  |  |  | <section id='instructions'> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | </section> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ## Tests
 | 
					
						
							|  |  |  | <section id='tests'> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ```yml | 
					
						
							| 
									
										
										
										
											2018-10-04 14:37:37 +01:00
										 |  |  | tests: | 
					
						
							|  |  |  |   - text: <code>euler379()</code> should return 132314136838185. | 
					
						
							| 
									
										
										
										
											2018-10-20 21:02:47 +03:00
										 |  |  |     testString: assert.strictEqual(euler379(), 132314136838185, '<code>euler379()</code> should return 132314136838185.'); | 
					
						
							| 
									
										
										
										
											2018-09-30 23:01:58 +01:00
										 |  |  | 
 | 
					
						
							|  |  |  | ``` | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | </section> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ## Challenge Seed
 | 
					
						
							|  |  |  | <section id='challengeSeed'> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | <div id='js-seed'> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ```js | 
					
						
							|  |  |  | function euler379() { | 
					
						
							|  |  |  |   // Good luck! | 
					
						
							|  |  |  |   return true; | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | euler379(); | 
					
						
							|  |  |  | ``` | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | </div> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | </section> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ## Solution
 | 
					
						
							|  |  |  | <section id='solution'> | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | ```js | 
					
						
							|  |  |  | // solution required | 
					
						
							|  |  |  | ``` | 
					
						
							|  |  |  | </section> |