$$1,000,000=1.20^{x-1}$$
$x=\log_{1.2}\left(1200000\right)\approx 76.775518819$
$x=\frac{i\times 2\pi n_{1}}{\ln(1.2)}+\log_{1.2}\left(1200000\right)$
$n_{1}\in \mathrm{Z}$