This is the correct answer. Congrats, @Scroogey. I wonder if you'd be interested in taking a look at these bitcoin math puzzles i've been doing too.
Also, for this question, I was hoping someone would solve it by drawing out the grid and writing the number of paths from each grid point, essentially working backwards recursively from the lower right to the upper left. There's an interesting connection between C(n,r) and triangular sums.
This is the correct answer. Congrats, @Scroogey. I wonder if you'd be interested in taking a look at these bitcoin math puzzles i've been doing too.
Also, for this question, I was hoping someone would solve it by drawing out the grid and writing the number of paths from each grid point, essentially working backwards recursively from the lower right to the upper left. There's an interesting connection between C(n,r) and triangular sums.