Definition:Subfactorial/Sequence

Examples of Factorials
The sequence of subfactorials begins:

$\begin{array}{r|r} n & !n \\ \hline 0 & 1 \\ 1 & 0 \\ 2 & 1 \\ 3 & 2 \\ 4 & 9 \\ 5 & 44 \\ 6 & 265 \\ 7 & 1 \, 854 \\ 8 & 14 \, 833 \\ \end{array}$