From charlesreid1

Very important number series occurring in combinatorics: https://en.wikipedia.org/wiki/Catalan_number

Recurrence relation:


C_0 = 1


C_{n+1} = \sum_{i=0}^{n} C_{i} C_{n-i}

Formula:


C_{n} = \dfrac{(2n)!}{(n+1)! n!}

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