Vandermonde polynomial

In algebra, the Vandermonde polynomial of an ordered set of n variables ${\displaystyle X_{1},\dots ,X_{n}}$, named after Alexandre-Théophile Vandermonde, is the polynomial:

(Some sources use the opposite order ${\displaystyle (X_{i}-X_{j})}$, which changes the sign ${\displaystyle {\binom {n}{2}}}$ times: thus in some dimensions the two formulae agree in sign, while in others they have opposite signs.)

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