Fermat polygonal number theorem

Fermat's polygonal number theorem states that every positive integer can be expressed as the sum of at most \( n \) \( n \)-gonal numbers. More specifically, for any positive integer \( n \), every positive integer can be represented as the sum of \( n \) or fewer \( n \)-gonal numbers. An \( n \)-gonal number is a number that can be arranged in a polygon with \( n \) sides.