V = 3.674, 6.791, 8.888, 9.667.....
    Sample = 2, 3, 4, 5.....

V(2) = a + 2b + 4c + 8d
    V(3) = a + 3b + 9c + 16d
    V(4) = a + 4b + 16c + 64d
    V(5) = a + 5b + 125c + 125d

a = -4.428
   b = 4.3756
   c = -0.06299
   d = -0.04966

V(3.5) = a + 3.5b + 12.25c + 42.875d
  V(3.5) = 7.186 Volts

V