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

Home > Just Math
Subtract 1, get a square (Posted on 2009-06-24) Difficulty: 2 of 5
By subtracting 1 from the positive base N integer having the form XYXYXYZY, we get a perfect square. It is known that each of X, Y and Z represents a different base N digit from 0 to N-1, and X is nonzero.

What are the integer value(s) of N, with 3 ≤ N ≤ 16 for which this is possible?

No Solution Yet Submitted by K Sengupta    
No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
general solution (no proof yet) | Comment 2 of 4 |

in exploring further bases up to n=36 I found a pattern among solutions, namely

x=n-2 y=2 z=0 always seems to give a perfect square plus 1 for all bases n.  Of course in this particular problem n=4 must be excluded because then x=y=2.  I am currently working on a proof of this, but the most obvious aproach of trying to factor the polynomial given by xyxyxyzy when expanded out in base n bore no fruit.

Edited on June 24, 2009, 2:45 pm
  Posted by Daniel on 2009-06-24 14:43:38

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