Calculate the number of W+W- pairs where the W+ boson decays into an antimuon and the W- boson decays into an electron or where the W boson decays into a muon and the W boson decays into a positron, which have been produced at the ATLAS experiment in Run 2 of the LHC. During Run 2, the ATLAS experiment has collected an integrated luminosity of 139 fb-1. The W+W- cross section at the LHC is oW+W- = 126 pb.