👉 In mathematics, an epitrachelion is a special kind of hypergeometric function. It is defined as follows: Theorem (Epitrachelion): Let f(z) be a meromorphic function in the upper half-plane C + i0 with poles at z1 and z2 = -i0. Then f(z) has an epitrachelion of order 3. This theorem can also be stated in terms of the Dirichlet series representation for the Taylor coefficients of the