Z1 = 1, Z2 = 36, Z3, Z4 = 38346, Z5 = 1246285 … Zn, find Z3 and Zn?

$Z_1 = 1, Z_2 = 36, Z_3=?, Z_4 = 38346, Z_5 = 1246285, …$, find $Z_3$ and $Z_n$?

For info I have already $Z_n$; I just want to compare the results.

And if you want more value from this series I can provide it.

Here are more details about $Z_n$:

$Z_n$ increases exponentially at a certain level and then decreases towards $0$.

$Z_n$ is the whole part of a function of $n$.

Here are more values ​​of $Z_n$:

$Z_0$=0

$Z6 = 40504909,$
$Z7 = 1316424317,$
$Z8 = 42784149984.$