We define a function in
terms of quotients of the p-adic gamma function which generalizes earlier work of the
author on extending hypergeometric functions over finite fields to the p-adic setting.
We prove, for primes p > 3, that the trace of Frobenius of any elliptic curve over 𝔽p,
whose j-invariant does not equal 0 or 1728, is just a special value of this
function. This generalizes results of Fuselier and Lennon which evaluate the
trace of Frobenius in terms of hypergeometric functions over 𝔽p when p ≡ 1(mod12).
Keywords
elliptic curves, p-adic gamma
function, trace of Frobenius, hypergeometric functions,
modular forms