Pythagorean Odds

Algebra Level 1

Consider the following sequence of all positive odd numbers: $1, 3, 5, 7, 9, 11, 13, \ldots.$

The sum of the first 3 terms is equal to 9: $1+3+5=9.$
The sum of the first 5 terms is equal to 25: $1+3+5+7+9=25.$

What is the sum of the first 99 terms of the sequence?