Find the nth term of this sequence 1,5,9,13,17-think it’s 4 but not sure x

It would be 33 because youre adding 4 each time 

We need to find the nth term of the sequence, so it's not a number! But the rule of that sequence.

That sequence is an arithmetic sequence which has a first term of 1, a second term of 5
a₁ = 1
a₂ = 5
The difference will be
d = a₂ - a₁
d = 5 - 1
d = 4

General formula to find the nth term of the sequence is written below.
un = a₁ + d(n - 1)

Input the value of a₁ and d to the formula
un = a₁ + d(n - 1)
un = 1 + 4(n - 1)
un = 1 + 4n - 4
un = 4n - 3

un = 4n - 3
This is the rule for nth term of the sequence