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Lobb's generalisation of Catalan's parenthesisation problem revisited

Published online by Cambridge University Press:  23 January 2015

Thomas Koshy*
Affiliation:
Department of Mathematics, Framingham State University, Framingham, MA 01701-9101, USA

Extract

In 1838, the Belgian mathematician Eugene C. Catalan (1814-1894) discovered that the number Cn of well-fonned sequences, with n pairs of left and right parentheses, is given by where n > 0 [1, 2]. For example, there are exactly five well-formed sequences with three pairs of left and right parentheses: ()()(), ()(()), (())(), (()()), ((())). The case n = 0 yields the null sequence, often denoted by λ. Notice that ()) and ((()()), for example, are not correctly parenthesised.

Type
Articles
Copyright
Copyright © The Mathematical Association 2012

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