'n' अचिह्नित (unlabeled) नोड्स के साथ कितने संरचनात्मक रूप से भिन्न बाइनरी ट्री संभव हैं?

What is the total sum of lengths of all suffixes of a string X of length 'N'?

The number of different unlabeled binary trees with 5 nodes is:

Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R): Assertion (A): If a department contains 13 professors, then at least two of the professors were born in the same month. Reason (R): The Pigeonhole Principle states that if there are more 'pigeons' than 'pigeonholes', there must be at least one pigeonhole containing more than one pigeon. In light of the above statements, choose the correct answer from the options given below: