Typecho博客
https://www.diyifanwen.com/fanwen/dangyuanxindetihui/2665516.htm
https://www.diyifanwen.com/fanwen/dangyuanxindetihui/2665516.htm
https://www.diyifanwen.com/fanwen/dangkexindetihui/2661093.htm
https://zhidao.baidu.com/question/585243762.html
try a try
$ sum_{d|n} mu(d) = [n==1] $
$ x $
$ sum_{d|n} phi(d) = n $
[sum_{d|n} mu(d) = [n==1]
]
[egin{equation}
sum_{d|n} phi(d) = n
end{equation}
]
[[egin{aligned}
x ={}& a+b+c+{} \
&d+e+f+g
end{aligned}]
]
ac is ok
#include<bits/stdc++.h>
int main() {
std::cout << "Hello!
";
}
$ sum_{k=1}{log_{4}{N}}{frac{3}{4^{k}}}Nk $
[egin{cases}
3x + 5y + z \
7x - 2y + 4z \
-6x + 3y + 2z
end{cases}
]
[egin{array}
overline{a+b+c} \
underline{a+b+c} \
overleftarrow{a+b} \
underleftarrow{a+b} \
underleftrightarrow{a+b} \
vec x = vec{AB} \
overbrace {a+b}^ ext{a,b} \
a+
lap{overbrace{phantom{b+c+d}}^m}b+underbrace{c+d+e}_n+f
end{array}
]
[egin{array}
sum_{d|n} mu(d) = [n==1]
end{array}
]