From: Ludovicus on
Discrete Exponential Distribution:
Resulting fron assigning as ordinate the area under the Exponential
Curve within consecutive
integer abscissae.
f(k) = [ n(1 - exp(-1/M).exp(-k/M) ]

n = Number of data. k = integer abscissa
M = Mean of integer abscissae ; [ ] = floor

Ludovicus