Triangular number
A triangular number or triangle number (Tn) is a number of the form n(n + 1)/2 where n is a nonnegative integer. It equals the sum of integers starting at 1 up to n, and is the amount of objects in a dense planar equilateral arrangement. A superparticular ratio whose numerator is a triangular number is a triangle-particular.
Triangular numbers are used in the formation of highschool scales.
