On the Fourier Coefficients of the Modular Invariant (j−123)1/2

1. Let H = {z = x + iy : y > 0} be the upper half of the complex plane and let x = exp2πiz. The Fourier coefficients c(n) of the modular invariant (1.1) j ( z )   =   x − 1   +   ∑ 1 ∞ c ( n ) x n https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203747018/bef25d74-ef02-4914-ac4f-27ec89fc30ac/content/eq799.tif"/>