It was first used by Max Bense at the opening of the first exhibition of computer art at his institute in Stuttgart. The 5th of February, 1965. There and then, he coined that term. In the form of Generative Aesthetics.
Frieder Nake, Frieder Nake on “Machinic” Miracles
Frieder Nake represents an incredible movement that was born in Stuttgart, Germany.
Michael Spalter, Michael Spalter on 1960s Computer Art