Question

What is the recursive formula for the sequence? 10, 14, 18, 22, 26

Answer 1

We have an arithmetic sequence  with common difference of 4; then, d = 4 and a1 = 4;
We have the formula an = a1 + (n-1)xd;
Finally, an = 10 + (n-1)x4 = 4n + 6;

Answer 2

Add 4 each time
the nth term is $a_n$ or f(n)
the next term after that is $a_{n+1}$ or f(n+1)

so each term is 4 more than previous
basically
$a_{n+1}=4+a_n$ or
f(n+1)=4+f(n)
same thing