Hockey-stick identity

In combinatorial mathematics, the identity is known as the hockey-stick or Christmas stocking identity. That name stems from the graphical representation of the identity on Pascal's triangle: when the addends represented in the summation and the sum itself are highlighted, the shape revealed is vaguely reminiscent of those objects.

Hockey-stick identity

In combinatorial mathematics, the identity is known as the hockey-stick or Christmas stocking identity. That name stems from the graphical representation of the identity on Pascal's triangle: when the addends represented in the summation and the sum itself are highlighted, the shape revealed is vaguely reminiscent of those objects.