[[Pascal's triangleTriangle]] is a triangula array of numbers which is well-known in mathematics. The number at the n-th row and r-th column in the array is the value of combination :<texcode> {n \choose k} </texcode> or <texcode> \binom{n}{k} </texcode>.
More detailed explanation, you may read wikipedia.
* '''[https://en.wikipedia.org/wiki/Pascal%27s_triangle Pascal's Triangle in Wikipedia]'''