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?

See The Solution Submitted by Math Man    
No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
re(3): Answer: for any composite, odd or even Comment 6 of 6 |
(In reply to re(2): Answer: for any composite, odd or even by Ady TZIDON)

Oh.  Now that it has been pointed out, it is both clever and obvious.  

Thanks, Ady!

  Posted by Steve Herman on 2013-07-25 09:31:14
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (5)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2018 by Animus Pactum Consulting. All rights reserved. Privacy Information