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Sum of poisson probabilities

  1. Dec 3, 2015 #1
    Is there a closed form expression for the sum:

    Σx2/n! from 0 to N

    for N=∞ it is an exponential but what about the finite case?
  2. jcsd
  3. Dec 4, 2015 #2

    Buzz Bloom

    User Avatar
    Gold Member

    Hi aaaa202:

    The finite sum is a polynomial expression. According to some definitions of "close form" a polynomial is closed. I am pretty sure there is no simpler representational, as there is for the infinite sum.

    BTW: You have a typo in the equation:
    The exponent should be "n", not "2".

    Good luck.

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