Question 882250
<pre>

Double x=0 and get 0, then add 1 and you get y=1.
Double x=1 and get 1, then add 1 and you get y=3.
Double x=2 and get 4, then add 1 and you get y=5.
Double x=3 and get 6, then add 1 and you get y=7.
Double x=4 and get 8, then add 1 and you get y=9.

So if you double x, then add 1, you'll get y.

So

2x + 1 = y

or turn it around,

y = 2x + 1

Edwin</pre>