A pattern of squares is shown. It changes by the same amount in each step. Look at the figure.

A pattern of squares is shown. Each set of squares is labeled. One is one square. Two is one square in column one and two in columns two. Three is two squares in column one and three in column two. Four is three squares in column one and four in column two.

Kwan has determined that he can use the expression
to find the number of squares for any step number
. Find an equivalent expression that Kwan can also use.

Enter the correct answer in the box.