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Exponential Sum Function

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ExponentialSumFunction

The exponential sum function e_n(x), sometimes also denoted exp_n(x), is defined by

e_n(x)=sum_(k=0)^(n)(x^k)/(k!)
(1)
=(e^xGamma(n+1,x))/(Gamma(n+1)),
(2)

where Gamma(a,x) is the upper incomplete gamma function and Gamma(x) is the (complete) gamma function.

See also

Gamma Function, Incomplete Gamma Function

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Cite this as:

Weisstein, Eric W. "Exponential Sum Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ExponentialSumFunction.html

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