Results 1 to 3 of 3

Math Help - Complex prime problem

  1. #1
    Newbie
    Joined
    Apr 2011
    Posts
    3

    Complex prime problem

    I am having great difficulty figuring the followin problem. Your help is appreciated!

    Find all primes p such that 2011p = 2+3+4+...+n for some positive integer n

    I've goten as far as 2011p = (n(n+1)/2)-1

    p= ((n(n+1)/2)-1)/2011 and plugging in various numbers for n.

    Am i on the right track?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Banned
    Joined
    Oct 2009
    Posts
    4,261
    Thanks
    2
    Quote Originally Posted by fernipascual View Post
    I am having great difficulty figuring the followin problem. Your help is appreciated!

    Find all primes p such that 2011p = 2+3+4+...+n for some positive integer n

    I've goten as far as 2011p = (n(n+1)/2)-1

    p= ((n(n+1)/2)-1)/2011 and plugging in various numbers for n.

    Am i on the right track?


    I think you are. Observe that \displaystyle{2,011p=\frac{n(n+1)}{2}-1=\frac{(n+2)(n-1)}{2}} ...

    The above already tells you that if p>2 then either n=0\!\!\pmod 4\mbox{ or else } n=3\!\!\pmod 4 .

    Tonio
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Apr 2011
    Posts
    3
    Thanks much Tonio. What does mod 4 mean? Is n=3 the only answer?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Birthday Problem; Prime Number Problem
    Posted in the Algebra Forum
    Replies: 9
    Last Post: January 8th 2012, 12:35 PM
  2. Replies: 1
    Last Post: October 22nd 2011, 01:37 PM
  3. relatively prime problem
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: April 30th 2009, 07:13 AM
  4. Prime problem
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: January 21st 2008, 01:17 PM
  5. Complex prime numbers?
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: September 20th 2007, 07:56 PM

Search Tags


/mathhelpforum @mathhelpforum