$\pi$-formulas with free parameters
  In terms of the hypergeometric method, we give the extensions of two known series for $\pi$. Further, other twenty-nine summation formulas for $\pi$, $\pi^2$ and $1/\pi$ with free parameters are also derived in the same way. 
Chuan Wei, Dianxuan Gong, Jianbo Li
math.CO