- More efficient formula for computing `superfactorial(n)` and `lnsuperfactorial(n)`.
- More efficient formula for computing `superfactorial(n)` and `lnsuperfactorial(n)`.

Formula:

	superfactorial(n) == prod(1..n, {|k| k**(n - k + 1) })

This is slightly faster than multiplying all the factorials up to `n!`.

Similarily for `lnsuperfactorial(n)`, we have:

	lnsuperfactorial(n) =~= sum(1..n, {|k| log(k) * (n - k + 1) })

trizen/sidef,trizen/sidef,trizen/sidef,trizen/sidef