N=6: sign changes of R on b in [0.30, 0.94] (step 0.02): []
N=10: sign changes of R on b in [0.30, 0.94] (step 0.02): [('0.54', '0.56')]
    root b = 0.5543486017300704561911   R there = 2.64e-44   max |A_ant/A| at 3 members = 2.64e-44
N=14: sign changes of R on b in [0.30, 0.94] (step 0.02): [('0.56', '0.58')]
    root b = 0.5661108682363198545677   R there = 3.66e-44   max |A_ant/A| at 3 members = 3.66e-44
N=18: sign changes of R on b in [0.30, 0.94] (step 0.02): [('0.56', '0.58')]
    root b = 0.5706649669806133282324   R there = -8.38e-45   max |A_ant/A| at 3 members = 8.38e-45
A_dag/A_ant for N=6, (a,b)=(1,0.8): 2.1875
A_dag/A_ant for N=10, (a,b)=(1,0.5): -74.4175010170852
closed form for N = 6 at (1, 0.8): (4a^2-b^2)/(4a^3 b^2 (2b-a)) = 2.1875
