@inproceedings{Shih2005RecountingDI,
title={Recounting Dyons in N = 4 String Theory},
author={David Shih and Andrew Strominger and Xi Yin},
year={2005}
}

A recently discovered relation between 4D and 5D black holes is used to derive weighted BPS black hole degeneracies for 4D N = 4 string theory from the well-known 5D degeneracies. They are found to be given by the Fourier coefficients of the unique weight 10 automorphic form of the modular group Sp(2, Z). This result agrees exactly with a conjecture made some years ago by Dijkgraaf, Verlinde and Verlinde.