From 4de6c0acec40732fcb18ae67e9cc5d8f28248da1 Mon Sep 17 00:00:00 2001
From: kenlig <wodeyouxhe@qq.com>
Date: Sat, 22 Jun 2019 17:25:05 +0800
Subject: [PATCH] Update catalan.md

---
 docs/math/catalan.md | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/docs/math/catalan.md b/docs/math/catalan.md
index 80de29eb..5333e99a 100644
--- a/docs/math/catalan.md
+++ b/docs/math/catalan.md
@@ -24,3 +24,25 @@
 $$
 H_n=\frac{C_{2n}^{n}}{n+1}(n=1,2,3,\cdots)
 $$
+
+或者是
+
+$$
+H_n=H_0*H_(n-1)+H_1*H_(n-2)+...+H_(n-1)*H_0
+$$
+
+$$
+其中有 n>=2 且 H_0=H_1=1
+$$
+
+或者是
+
+$$
+H_n=H_(n-1)*(4*n-2)/(n+1)
+$$
+
+或者是
+
+$$
+H_n=C_{2n}^{n}-C_{2n}^{n-1}
+$$
-- 
2.11.0