General function to compute the k-th moment of the MOEZipf distribution for any integer value \(k \geq 1\),
when it exists. The k-th moment exists if and only if \(\alpha > k + 1\).
For k = 1, this function returns the same value as the moezipfMean function.
Value of the \(\alpha\) parameter (\(\alpha > k + 1\)).
beta
Value of the \(\beta\) parameter (\(\beta > 0\)).
tolerance
Tolerance used in the calculations (default = \(10^{-4}\)).
Value
A positive real value corresponding to the k-th moment of the distribution.
Details
The k-th moment is computed by calculating the partial sums of the serie, and stopping when two
consecutive partial sums differ less than the tolerance value.
The value of the last partial sum is returned.