Triangular Numbers, Formula to Find the nth Term

Triangular Numbers 1, 3, 6, 10, 15 Non-Linear Pattern is a triangular number pattern. You add one more each time. I go over three example problems: Find the 16th triangular number, which triangle number is 78? and find the 21st triangle number. Branch of mathematics called sequence and series. I go over progressions and three ways to create them: a list, as a general term, or as a recursion. n(n+1)/2