[tex]a=15^{2018}\\
\\ a=15 \cdot 15 \cdot 15^{2016}\\
\\ a=225 \cdot 15^{2016}\\
\\ a=(1+8+27+64+125)\cdot 15^{2016}\\
\\ a=(1^{3}+2^{3}+3^{3}+4^{3}+5^{3})\cdot (15^{672})^{3}\\
\\ a=1^{3}\cdot(15^{672})^{3}+2^{3}\cdot(15^{672})^{3}+3^{3}\cdot(15^{672})^{3}+4^{3}\cdot(15^{672})^{3}+5^{3}\cdot(15^{672})^{3}\\
\\ a=(1\cdot15^{672})^{3}+(2\cdot15^{672})^{3}+(3\cdot15^{672})^{3}+(4\cdot15^{672})^{3}+(5\cdot15^{672})^{3}[/tex]
