=+14.5 Problems 371 regardless of which N{} is chosen [76]. Setting r = p(1

=+14.5 Problems 371 regardless of which β ∈ Nα\{α} is chosen [76]. Setting r = p(1 − p), verify the recurrence relation wn+1,d12,d13 = r(wn,d12−1,d13 + wn,d12,d13−1 + wn,d12−1,d13−1)

+ (1 − 3r)wn,d12,d13 .

Under the natural initial conditions, w0,d12,d13 is 1 when d12 = d13 = 0 and 0 otherwise.