Input is 1,2,3,4,5,6 and output is 5,8,11,14,17,20 what is the rule and equation

Notice that each output is increased by 3 and starts with 5. We can predict that when input is 0, the output would be 2.

So the rule would be multiply the input by 3 then add 2. The equation would be f (n) = 3n+2