span><span class="w"> </span><span class="n">x</span><span class="p">(</span><span class="n">jx</span><span class="p">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">x</span><span class="p">(</span><span class="n">jx</span><span class="p">)</span><span class="o">*</span><span class="n">ap</span><span class="p">(</span><span class="n">kk</span><span class="o">+</span><span class="n">j</span><span class="o">-</span><span class="mi">1</span><span class="p">)</spa