2(1H)-Pyridinone, 4-hydroxy-1-.beta.-D-ribofuranosyl-, compd. with 2(1H)-pyrimidinone, 4-amino-1-[(2R,5S)-tetrahydro-5-(hydroxymethyl)-2-furanyl]- (1:1) AIDS-154464 AIDS154464 ddC & 3-DU