A triangular number Tn is a figurate number that can be represented in the form of an equilateral triangular grid of elements such that every subsequent row contains an element more than the previous one. The representation of the numbers in the form of equilateral triangle arranged in a series or sequence. These numbers are in a sequence of 1, 3, 6, 10, 15, 21, 28, 36, 45, and so on. The numbers in the triangular pattern are represented by dots. The sum of the previous number and the order of succeeding number results in the sequence of triangular numbers.