User:JWB/Nuclide chart with skew 1.5

One vertical step down adds one proton and subtracts 1.5 neutrons.

Adding one proton goes down one step and left 1.5 steps.

Adding one proton and one neutron goes down one step and left half a step.

Isobars (same-mass nuclides) differ by -2.5n horizontal and +n vertical.