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Math Help - What is the symbol for summing odd numbers?

  1. #1
    Member billym's Avatar
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    What is the symbol for summing odd numbers?

    What would I use instead of \sum if I just wanted to sum odd values for some number n through k?
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  2. #2
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    Quote Originally Posted by billym View Post
    What would I use instead of \sum if I just wanted to sum odd values for some number n through k?


    \sum_{i=0}^r 2i+n

    Where n is the odd number you want to start with

    You would need to decide what r would be so that you stopped at the correct value

     <br />
2r+n=k<br />
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  3. #3
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    Quote Originally Posted by billym View Post
    What would I use instead of \sum if I just wanted to sum odd values for some number n through k?
    I think you mean start from n and end at k by 2's. You can do this a few ways.

    \sum_{n=1,3,5...}^{k} a_n works but looks bad.

    If you want to sum over all odds you can write \sum_{odds}

    If you want to skip terms in a sequence you can write

    \sum_{n}^{k} a_{2n}

    I don't know exactly what you meant but those are some of my guesses.
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    Quote Originally Posted by billym View Post
    What would I use instead of \sum if I just wanted to sum odd values for some number n through k?
    \sum\limits_{j = \left\lfloor {\frac{n}<br />
{2}} \right\rfloor }^{\left\lfloor {\frac{{k - 1}}<br />
{2}} \right\rfloor } {2j + 1}
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  5. #5
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    edit:nevermind
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  6. #6
    Member billym's Avatar
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    I think I'll go with Jameson's bad looking one. Does the job.
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