Proposition: Sum of Factorials (I)
The following sum of factorials holds for all natural numbers $n\in\mathbb N:$ $$\sum_{k=0}^nk\cdot k !=(n+1) !1.$$
Table of Contents
Proofs: 1
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References
Bibliography
 Modler, F.; Kreh, M.: "Tutorium Analysis 1 und Lineare Algebra 1", Springer Spektrum, 2018, 4th Edition