Square Sequence Formula: Identifying the Pattern Expression

Question

Which formula corresponds to the number of squares in the above sequence?

00:00 Find the sequence formula

00:03 Let's observe the number of squares in each term

00:21 Let's substitute the first term in equations and see if it fits

00:35 We can see that this formula doesn't fit

00:40 Let's continue with this method until we find the correct formula

00:51 This formula doesn't fit either

00:54 This formula fits the first term

00:59 And this formula also fits the first term

01:02 Let's check which formula also fits the second term

01:09 This formula doesn't fit the second term, so it's not the formula

01:23 And this is the solution to the question

$2n-1$