Lower fixed binomial coefficient → overlapping combination
$ \binom{A+i}{A} = \binom{A+i}{i} = H^{A+1}_i
$ \binom{A+i}{A} = H_A^{i+1}
The latter is also possible, but the former is a more natural form of Collapsing Duplicate Combinations since it is a form of placing a variable ball on a fixed frame. ---
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