1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Series and sequences problem

  1. Jan 27, 2008 #1
    1. The problem statement, all variables and given/known data

    I need to find three mathematical series, for the following patterns

    1) Sn= 1/n if n is odd, or 1 of n is even.

    2) Sn= 0,1,0,.5,1,0,1/3,2/3,0,1/4........

    3) Find a sequence (Sk) which is a subset of the natural numbers in which every positive integer appears infinitely many times......that is, for each n in the Natural numbers, Sk=n for infinately many k's. any ideas???????????????????

    2. Relevant equations

    I guess they're arent any relevant equations to these. I guess yuo jsut have to get the pattern

    3. The attempt at a solution

    well, I know the first two are similar and thats about all I know. they're not p-series, geometric, alternating, or anything like that so I'm kind of stuck

    The third one, well, I don't even kow what it means honestly, so can you at least give me a hint?? thanks.
  2. jcsd
  3. Jan 27, 2008 #2
    For 1), try thinking along the lines of

    (-1)^n =
    -1 & n\mbox{ is odd}\\
    1 & n\mbox{ is even}

    For 2), try thinking along the lines of the periodicity of [tex]\sin(x)[/tex].

    For 3), I'll have to refer you to the Wikipedia article on Hilbert's Paradox.
    Last edited: Jan 27, 2008
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Series and sequences problem
  1. Sequences and series (Replies: 2)

  2. Sequences and Series (Replies: 25)