Calculates the sum of a power series. Given an array of numbers
\[a₀, a₁, a₂, ... , aᵢ\], and the constants
m, the sum is calculated using the formula:
a₀ × x^n + a₁ × x^\(n+m\) + a₂ × x^\(n + 2 × m\) + ... + aᵢ × x^\(n + i × m\)
SERIES_SUM(numberx: Number, numbern: Number, numberm: Number, array: Array) => Number
The initial power to which to raise
The additive increment by which to increase the power to which
The array or range containing the coefficients of the power series.