Music Science Guy has published a guide to the Harmonic Table system - an alternate layout for music keyboards:

This is a “twice folded scale” whereupon we have notes evenly spaced out, in intervals called a major second, and fold them twice, first by octave, and then again, so that the octave family of harmonics(1, 2, 4, 8, 16, & 32), the green circles, are next to the Perfect Fifth family(3, 6, 12, 24), the Red circles.

This is the basis of the Wicki-Hayden (Wicki for short) key layout and design of the jammer keyboard. One big advantage is that one can press the two notes most used together in music with a single finger straddling the two.

If you’re puzzled by how these unique key layouts work, check it out.