(a) u = ln(2) + (a/r)^3 cos(3 theta)
  The 7 Feb 2014 blackboard answer is correct for a=1 only.
(b) The answer for the Fourier coefficients is (47) in H2.5 with a^n replaced by 1/a^n.
  The 7 Feb upper blackboard has the series written correctly.