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<div><span class="kw">theorem </span><a NAME="T28"><span class="comment"><font color="firebrick">:: BASEL_1:28</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">n</font> being   <a href="ordinal1.html#NM6" title="ORDINAL1:NM.6">Nat</a> holds   <a href="rvsum_1.html#K12" title="RVSUM_1:func.12">sqr</a> <span class="p1">(<span class="default"><a href="basel_1.html#K3" title="BASEL_1:func.3">cot</a> <span class="p2">(<span class="default"><a href="basel_1.html#K5" title="BASEL_1:func.5">x_r-seq</a> <font color="Olive" title="b1">n</font></span>)</span></span>)</span> is  <a href="funct_1.html#V2" title="FUNCT_1:attr.2">one-to-one</a> </div></div>
