\version "2.18.0"
\score {
  {
    $(let ((random-state (seed->random-state (current-time))))

       (make-sequential-music
        (map (lambda (x)
               (let ((idx (random 12 random-state)))
                 (make-event-chord
                  (list
                   (make-music 'NoteEvent
                     'duration (ly:make-duration 2 0 1/1)
                     'pitch (ly:make-pitch
                             (quotient idx 7)
                             (remainder idx 7)
                             0))))))
          (make-list 24))))
  }
}