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Summation notation indexing

  1. Jan 28, 2010 #1
    [tex]\sum_{k=0}^{\infty}a_{k}(k+r)(k+r-1)x^{k-1} [/tex]

    I need to get my x term to look like xn.

    If I set n = k-1, then that makes my index start at n = -1, which is silly. What can I do?
  2. jcsd
  3. Jan 28, 2010 #2
    Why is that silly? When k = 0, you have x^-1 in your original summation.
  4. Jan 29, 2010 #3
    It doesn't make sense when I'm using it in the Frobenius method.
    Last edited: Jan 29, 2010
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