# In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$
## In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$
### In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$
#### In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$
##### In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$
###### In header: $\sum_{k=1}^{\infty} \sfrac{1}{k^2} = \sfrac{\pi^2}{6}$