1, 4, 9, 16, 25, 36, ?

These numbers are:

• $1^2 = 1$

• $2^2 = 4$

• $3^2 = 9$

• $4^2 = 16$

• $5^2 = 25$

• $6^2 = 36$

So, the pattern is: squares of natural numbers

Next term = 7^2 = 49$$72=497^2 = 49