| blob | 1632a28317965b38129d4e5f2717f16f39d67466 |
1 <span class="re3">$$ \<a href="http://www.golatex.de/wiki/index.php?title=%5Csum"><span class="kw1">sum</span></a>_<span class="sy0">{</span><span class="re9">i = 1</span><span class="sy0">}</span>^n a_i = <span class="sy0">\</span><a href="http://www.golatex.de/wiki/index.php?title=%5Cfrac"><span class="kw1">frac</span></a><span class="sy0">{</span><span class="re9">n(a_1 + a_n) </span><span class="sy0">}{</span><span class="re9">2</span><span class="sy0">}</span> $</span>$