Kolmnurkseid

Kolmnurkseid, also known as triangular numbers, are a sequence of numbers that can be represented by an equilateral triangle with a dot at each vertex and each subsequent row containing one more dot than the previous row. The nth triangular number is the sum of the first n natural numbers. The formula to calculate the nth triangular number is n(n + 1)/2. For example, the 5th triangular number is 5(5 + 1)/2 = 15. Triangular numbers have various applications in mathematics, including in the study of combinatorics and number theory. They are also used in the construction of geometric shapes and in the analysis of algorithms. The sequence of triangular numbers starts with 1, 3, 6, 10, 15, and so on.