Certain values of Gaussian hypergeometric series and a family of algebraic curves

Abstract

Let $\lambda \in \mathbb{Q}\setminus \{0,-1\}$ and $l\ge 2$. Denote by $C_{l,\lambda }$ the nonsingular projective algebraic curve over $\mathbb{Q}$ with affine equation given by $$y^l=(x-1)(x^2+\lambda ).$$ In this paper we give a relation between the number of points on $C_{l,\lambda }$ over a finite field and Gaussian hypergeometric series. We also give an alternate proof of a result of McCarthy (2010). We find some special values of ${}_3{F}_2$ and ${}_2{F}_1$ Gaussian hypergeometric series. Finally we evaluate the value of ${}_3{F}_2(4)$ which extends a result of Ono (1998).

14 pages