x
, n, m and a, returns the power series sum a_{1}x^{n} + a_{2}x^{(n+m)} + … + a_{i}x^{(n+(i1)m)}, where i is the number of entries in range 'a'.
Sample usage
SERIESSUM(1,0,1,{FACT(0),FACT(1),FACT(2),FACT(3),FACT(4)})
SERIESSUM(A2,0,2,B2:B10)
Syntax
SERIESSUM(x, n, m, a)

x
– The input to the power series. Varies depending on the type of approximation; may be angle, exponent or some other value. 
n
– The initial power to which x is raised in the power series. 
m
– The additive increment by which x is increased. 
a
– The array or range containing the coefficients of the power series.
Notes
 Power series may be used to approximate various constants and functions, including e (Euler's number), logarithms, integrals, trigonometric functions, etc. However, this function is usually used for custom userdefined models.
See also
SUMSQ
: Returns the sum of the squares of a series of numbers and/or cells.
SUMIF
: Returns a conditional sum across a range.
SUM
: Returns the sum of a series of numbers and/or cells.
QUOTIENT
: Returns one number divided by another, without the remainder.
PRODUCT
: Returns the result of multiplying a series of numbers together.
MULTIPLY
: Returns the product of two numbers. Equivalent to the '*' operator.
MINUS
: Returns the difference of two numbers. Equivalent to the '' operator.
DIVIDE
: Returns one number divided by another. Equivalent to the '/' operator.
ADD
: Returns the sum of two numbers. Equivalent to the '+' operator.