Catalan number

The C5 = 42 noncrossing partitions of a 5-element set (below, the other 10 of the 52 partitions)

Lattice of the 14 Dyck words of length 8 - ( and ) interpreted as up and down

The associahedron of order 4 with the C4=14 full binary trees with 5 leaves

In combinatorial mathematics, the Catalan numbers form a sequence of natural numbers that occur in various counting problems, often involving recursively-defined objects. They are named after the Belgian mathematician Eugène Charles Catalan (1814–1894).

单词	Catalan Numbers
释义	Catalan Numbers 原声例句凯莉日记第1季 Especially the rows with the catalan numbers. 尤其喜欢加泰隆数那几行。英语百科 Catalan number In combinatorial mathematics, the Catalan numbers form a sequence of natural numbers that occur in various counting problems, often involving recursively-defined objects. They are named after the Belgian mathematician Eugène Charles Catalan (1814–1894).
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Catalan Numbers

Catalan number