Question 773376
3 9 4 5 25 20 21 441
<pre>
The pattern is, starting with 3 

Square, subtract 5, add 1.  

Repeat those three steps over and over:

Start with 3

Square, get 9
Subtract 5, get 4
Add 1, get 5

Square, get 25
Subtract 5, get 20
Add 1, get 21

Square, get 441
Subtract 5, get 436 

Edwin</pre>