\begin{aligned}h(a,b,c,n)&=h(a\ mod\ c,\ b\ mod\ c,\ c,\ n)\\&+2\left\lfloor\frac{b}{c}\right\rfloor f(a\ mod\ c,\ b\ mod\ c,\ c,\ n)+2\left\lfloor\frac{a}{c}\right\rfloor g(a\ mod\ c,\ b\ mod\ c,\ c,\ n)\\&+\left\lfloor\frac{a}{c}\right\rfloor^2\frac{n(n+1)(2n+1)}{6}+\left\lfloor\frac{b
# latex加粗字体
[TOC]
## 加粗
```latex
$\bold{f(L,R)=R-L+1}$
```
效果:

## 加粗斜体
```latex
$\symbol{f(L,R)=R-L+1}$
```
效