Pascal's Triangle and Its Relatives

Background

Pascal's Triangle Mod 3

The remainders of division by 3 are 0, 1, and 2. Here are some views of Pascal's triangle (mod 3). Here we shade the numbers
congruent to 0 congruent to 1
congruent to 2 congruent to 1 or 2
Alone, the numbers congruent to 1 (mod 3) or to 2 (mod 3) do not form a clean pattern, but those congruent to 1 or 2 (mod 3) do.
The Pascal's triangle coefficients congruent to 1 or 2 (mod 3) form a relative of the gasket, consisting of 6 pieces, each scaled by a factor of 1/3, so with dimension log(6)/log(3).
Because this dimension is < 2, we see again that in the n -> infinity limit, the probability of finding a Pascal's triangle coefficient that is not a multiple of 3 is 0.

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