KnowraHockey-stick identityLinked fromLinked fromThe 3 pages that link to Hockey-stick identity, each with the reason it gives.All 3Broader topic 2Compared with 1Pascal's triangleBroader topic: A diagonal sum forms a recognizable pattern within the array.Combinatorial proofBroader topic: The same subset can be counted by its largest selected element or in one unrestricted choice.