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

Home > Just Math
Three Power Verification (Posted on 2016-01-20) Difficulty: 3 of 5
M is a positive integer such that 4M + 2M +1 is a prime number.

Can there be any instance where M is not a power of 3?

Give reasons for your answer.

No Solution Yet Submitted by K Sengupta    
No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution | Comment 1 of 4
It suffices to consider the expression mod7. The cycle is {0,0,3}; so unless m=0,1, or a multiple of 3, m is divisible by 7, and so cannot be prime.
  Posted by broll on 2016-01-20 22:28:29
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 (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2021 by Animus Pactum Consulting. All rights reserved. Privacy Information