Every number hides a melody. Run the Collatz rule and let each step strike a note: the pitch follows the altitude of the hailstone on a log scale, snapped to a pentatonic scale so the storm sings instead of screams. Odd steps ring bright as the number leaps up; even steps answer softly as it falls. When the flight lands on 1, the box resolves to its root chord. Paste a number as big as you dare.
Duet mode: give a second seed and it plays in the right ear
while the first plays in the left. Try 12 and 13: three notes in, their
flights collide at the number 10 and the two melodies lock into unison for the rest of the fall.
Merging trajectories are the deep structure of the conjecture, and your ears find the merge
point faster than your eyes.