Painting numbers from 1 to infinity (or until death anyway).
From Futility Closet.
From 1965 to his death in 2011, Roman Opałka painted whole numbers starting from the number 1 and in sequential order on a series of canvases entitled “1965 / 1 – ∞.” He would declare, “All my work is a single thing, the description from number one to infinity. A single thing, a single life.” He made it to 5607249.
For more, see this link.