Problem: Starting in the top-left corner of a 20×20 grid, and only being able to move right and down, how many routes are there to the bottom-right corner? At first glance, this seems like a classic dynamic programming or pathfinding problem. But I took a different approach - let the computer explore small cases, then use pattern recognition to crack the larger problem. from itertools import permutations import math from math import factorial dictionary_x = {} list_x = [0, 1