本帖最后由 王守恩 于 2021-8-2 17:35 编辑
这80个数这样去找,会方便些(只要统计0就可以)。
\(6C_{n}^6\)={0,0,0,0,0,0}(本行有6个0,余同)
\(6C_{n}^4C_{n}^2\)={0,0,0,0,3,3}+{0,0,3,3,3,3}(本行有6个0)
\(6C_{n}^3C_{n}^3\)={0,0,0,2,2,2}+{0,0,0,4,4,4}(本行有6个0)
\(12C_{n}^4C_{n}^1C_{n}^1\)={0,0,0,0,1,5}+{0,0,0,0,2,4}+{0,1,1,1,1,2}+{0,2,2,2,2,4}+{0,2,4,4,4,4,}+{0,4,5,5,5,5}
\(12C_{n}^3C_{n}^2C_{n}^1\)={0,0,0,1,1,4}+{0,0,0,2,5,5}+{0,0,1,1,1,3}+{0,0,3,5,5,5}+{0,2,2,2,3,3}+{0,3,3,4,4,4}
\(8C_{n}^2C_{n}^2C_{n}^2\)={0,0,1,1,2,2}+{0,0,1,1,5,5}+{0,0,2,2,4,4}+{0,0,4,4,5,5}(本行有8个0)
\(12C_{n}^3C_{n}^1C_{n}^1C_{n}^1\)={000123}{000345}{011145}{012225}{012333}{012555}{014445}{033345}
\(12C_{n}^2C_{n}^2C_{n}^1C_{n}^1\)={001335}{001344}{002334}{002235}{011244}{011335}{022355}{022455}
\(6C_{n}^2C_{n}^1C_{n}^1C_{n}^1C_{n}^1\)={0,0,1,2,4,5}+{0,1,1,2,3,5}+{0,1,2,2,3,4}+{0,1,3,4,5,5}+{0,2,3,4,4,5}
合计,\(6+6+6+12+12+8+12+12+6=80\) |