 Alternating factorial - Reference: Encyclopedia - Alternating factorialAn alternating factorial is the absolute value of the alternating sum of the first n factorials.
This is the same as their sum, with the odd-indexed factorials multiplied by −1 if n is even, and the even-indexed factorials multiplied by −1 if n is odd, resulting in an alternation of signs of the summands (or alternation of addition and subtraction operators, if preferred). To put it algebraically,
or with the recurrence relation
af(n) = n! − af(n − 1)
in whic ...
Including:
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