如題，例如相加為4的組合數有1+1+1+1，2+1+1，3+1，2+2，共四種。
其中3+1與1+3算同一種。請問如何推導相加為X的正整數組合數？
--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 114.44.4.122
※ 文章網址: https://www.ptt.cc/bbs/Math/M.1543592726.A.0C4.html
→
11/30 23:47, , 1F
11/30 23:47, 1F
推
12/01 00:03, , 2F
12/01 00:03, 2F
→
12/01 00:03, , 3F
12/01 00:03, 3F
→
12/01 00:05, , 4F
12/01 00:05, 4F
推
12/01 01:36, , 5F
12/01 01:36, 5F
→
12/01 01:36, , 6F
12/01 01:36, 6F
推
12/01 04:25, , 7F
12/01 04:25, 7F
→
12/01 10:17, , 8F
12/01 10:17, 8F