All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Numbers
Repunits and bases (Posted on 2013-07-24) Difficulty: 3 of 5
112=3 and 1113=13 are prime. However, 11114=85=5*17 and 111115=781=11*71 are not prime. What is the least number n>3 such that the repunit consisting of n 1's in base n is prime?

  Submitted by Math Man    
No Rating
Solution: (Hide)
19 since 111111111111111111119=109912203092239643840221 is prime.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re(3): Answer: for any composite, odd or evenSteve Herman2013-07-25 09:31:14
Hints/Tipsre(2): Answer: for any composite, odd or evenAdy TZIDON2013-07-24 15:36:40
Questionre(2): Answer:Steve Herman2013-07-24 12:53:15
Questionre: Answer:Charlie2013-07-24 12:42:29
Solutioncomputer solutionCharlie2013-07-24 12:40:09
Answer:broll2013-07-24 11:29:46
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (2)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information