Expostfacto function

The expostfacto function is a function invented by Tom Kreitzberg defined as \(\mathrm{expostfacto}(n) = n^{\mathrm{expostfacto}(n-1)!}\), where \(\mathrm{expostfacto}(1) = 1\).Really Big Numbers
== Values ==
The first few terms for the sequence \(\mathrm{expostfacto}(n)\) are shown below:
\begin{eqnarray}
\mathrm{expostfacto}(1) &=& 1 \\
\mathrm{expostfacto}(2) &=& 2^{1} = 2 \\
\mathrm{expostfacto}(3) &=& 3^{2} = 9 \\
\mathrm{expostfacto}(4) &=& 4^{362,880} \approx 3.38573599\times10^{218,475} \\
\mathrm{expostfacto}(5) &=& 5^{(4^{362,880})!} \approx 10^{10^{7.39698994\times10^{218,480}}} \\
\end{eqnarray}
Expostfacto function grows as fast as \(f_3(f_1(n))\) in the fast-growing hierarchy.
== Sources ==
== See also ==
*Exponential factorial
Category:Functions
Category:Factorials