$\begin{array}{l}\phantom{\phantom{;}2a\phantom{;}+1;}{\phantom{;}16a^{4}-8a^{3}+4a^{2}-2a\phantom{;}+1\phantom{;}\phantom{;}}\\\phantom{;}2a\phantom{;}+1\overline{\smash{)}\phantom{;}32a^{5}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}+1\phantom{;}\phantom{;}}\\\phantom{\phantom{;}2a\phantom{;}+1;}\underline{-32a^{5}-16a^{4}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-32a^{5}-16a^{4};}-16a^{4}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}+1\phantom{;}\phantom{;}\\\phantom{\phantom{;}2a\phantom{;}+1-;x^n;}\underline{\phantom{;}16a^{4}+8a^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;\phantom{;}16a^{4}+8a^{3}-;x^n;}\phantom{;}8a^{3}\phantom{-;x^n}\phantom{-;x^n}+1\phantom{;}\phantom{;}\\\phantom{\phantom{;}2a\phantom{;}+1-;x^n-;x^n;}\underline{-8a^{3}-4a^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;;-8a^{3}-4a^{2}-;x^n-;x^n;}-4a^{2}\phantom{-;x^n}+1\phantom{;}\phantom{;}\\\phantom{\phantom{;}2a\phantom{;}+1-;x^n-;x^n-;x^n;}\underline{\phantom{;}4a^{2}+2a\phantom{;}\phantom{-;x^n}}\\\phantom{;;;\phantom{;}4a^{2}+2a\phantom{;}-;x^n-;x^n-;x^n;}\phantom{;}2a\phantom{;}+1\phantom{;}\phantom{;}\\\phantom{\phantom{;}2a\phantom{;}+1-;x^n-;x^n-;x^n-;x^n;}\underline{-2a\phantom{;}-1\phantom{;}\phantom{;}}\\\phantom{;;;;-2a\phantom{;}-1\phantom{;}\phantom{;}-;x^n-;x^n-;x^n-;x^n;}\\\end{array}$

$16a^{4}-8a^{3}+4a^{2}-2a+1$