The maximum number of binary trees that can be formed with

The maximum number of binary trees that can be formed with three unlabelled nodes is

It is given that n = 3

1		²ⁿC_n
n + 1

1		⁶C₃
3 + 1

	1.6!	= 5
	4 × 3!3!

Therefore, there are 5 trees that can be formed with three unlabelled node.