Square numbers

Square numbers are numbers that start with one and increase in a pattern of squares like this:

As you move to the right each pattern is one row of dots higher and one column of dots wider. You can find the number of dots in each pattern by multiplying the number of dots in a row by the number of dots in a column. As the dots are in the pattern of a square, the number of dots in a row is the same as the number of dots in a column.

n	1	2	3	4	5
	1	4	9	18	25

The nth number in the sequence is given by