Question 979015
<pre>

{{{S[n]}}}{{{"=""}}}{{{(a[1](r^n-1))/(r-1)}}}

{{{S[20]}}}{{{"=""}}}{{{(25(2^20-1))/(2-1)}}}

{{{S[20]}}}{{{"=""}}}{{{(25(1048576-1))/1}}}

{{{S[20]}}}{{{"=""}}}{{{25(1048575)}}}

{{{S[20]}}}{{{"=""}}}{{{26214400}}}
<font size = 4><b>
Answer:  P26214400</font></b>

Edwin</pre>