Triangular numbers is a figurate number system that can be represented in the form of a triangular grid of points where the first row contains a single element and each subsequent row contains one more element than the previous one. The triangular numbers from that pattern are 1 followed by 1+2 followed by 1+2+3 and so on. From the pattern of the triangular numbers, this infinite serious starts with 1, 3, 6, 10, 15… With this pattern, calculated by counting, the next three terms would be 21, 28, and 36. To derive a formula from this pattern, we can see that x is repeated and the number goes up each time by one. After using the rules of the sequences and a few checks, the final formula results inx(x+1)2 where x is any natural number. I found this formula with the calculator with steps show below. To prove this formula, there is the typical guess and check formula where the number of dots in the next triangle is counted for. Strangely when noticed clearly, the triangular numbers can be found in the third diagonal of Pascal’s triangle, starting at row 3 as shown in the diagram. The first triangular number is 1, the second is 3, the third is 6, the forth is 10, and so on.
This following drawing below shows the triangular pattern of evenly space dots. In this first picture, the triangular numbers with three more terms is completed.
Solution One: Technology
The next step is to find a general statement that represents the nth number of dots in the triangular number series in terms of x.
Let X represent the stage and let Y