How to integrate $5^{5^{5^x}}5^{5^x}5^x$? How to integrate $5^{5^{5^x}}5^{5^x}5^x$ ?
I guess it's simple but can't figure it out !

Start with $5^x=y\implies5^x\cdot\ln5\ dx=dy$ to get
$$\ln5\int5^{5^{5^x}}5^{5^x}5^x=\int 5^{5^y}5^ydy$$
again set $5^y=u$
