Question 169224
I need to find a counterexample to the statement {{{4^n+1}}} 
is divisible by {{{5}}}. Can someone please show me how to do this.
<pre><font size = 4 color = "indigo"><b>
Start with {{{n=1}}}.

{{{4^1+1 = 4+1 = 5}}}

No. that's not it, because {{{5}}} is divisible by {{{5}}}.

So try {{{n=2}}}

{{{4^2+1=16+1=17}}}

There your counterexample. {{{17}}} is not divisible by {{{5}}}.

Edwin</pre>