Sums the first terms of a power series.


SERIESSUM(x, n, m, ar)
A power series may be represented as:

The SERIESSUM function calculates the sum of the first terms of such a series, where:
x is the variable,
n is the power of x for the first term,
m is the increment by which the power of x increases with each term, and
ar refers to a range containing the a coefficients of the terms to be included.


The following power series may be used to express the mathematical constant e raised to a power:

When x = 1, summing the terms in the series will approximate e. To sum the first 5 terms using SERIESSUM we should set:
x = 1
n = 0
m = 1
ar to B1:B5, where B1, B2, B3, B4, B5 contain respectively:
          = 1/FACT(0), = 1/FACT(1), = 1/FACT(2), = 1/FACT(3), = 1/FACT(4)

Now, using these values in the SERIESSUM function:
SERIESSUM(1, 0, 1, B1:B5)
returns 2.70833333333333, an approximation of e ( = 2.71828182845904...). Using more terms would give a closer approximation.

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