Add Catalan number to maths (#6845)
* Add Catalan number to maths
* updating DIRECTORY.md
* [pre-commit.ci] auto fixes from pre-commit.com hooks
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Jordan Rinder committed
5894554d41116af83152b1ea59fbf78303d87966
Parent: 660d2bb
Committed by GitHub <noreply@github.com>
on 10/8/2022, 10:28:17 PM