2: 0.500691360286
    3: 0.643353043366
    4: 0.683921596576
    7: 0.773401521605
   19: 0.797778382713
   37: 0.806994224018

2 3 4 7 19 37

Fit of radii by a power law r = a0*n^a1:
  a0 = 0.75214  a1 = -0.45680