This article describes and analyses the Ai Music Generation Challenge 2020, where seven participants competed to build artificial systems that generate the most plausible double jigs, as judged against the 365 published in The Dance Music of Ireland: O'Neill's 1001 (1907). The outcomes of this challenge demonstrate how music generation systems can be meaningfully evaluated, and furthermore that the generation of plausible double jigs has yet to be "solved". The article ends by reflecting on the challenge and considers the coming 2021 challenge, focused on a form of Swedish traditional dance music.