nFor a 2-letter search word, either letter can occur in either order at any
spacing, so the probability is about 33 x 33 =
nFor search words of 3 letters or more, the rule that the code-words appear
with equidistant spacing makes matches much
rarer. The 3rd letter must be exactly the
same distance from the 2nd as the 2nd from the 1st. N = 1089/21 = 52.