What is the most efficient way to determine the coefficients {a_{1}, a_{2}, ..., a_{21}} such that \Delta^{21} \mid T_{3} \equiv \sum_{i = 1}^{21} c_{i} \Delta^{i} (mod 2)?
I tried finding the q-series expansion of LHS and accordingly kept subtracting powers of \Delta to find the scalars, but is there a better way to do this?
By \Delta(z), I mean the Ramanujan Delta function which is the 24th power of Dedekind eta function.