I just created a solver for the 4x4 case, also in google sheets... Who would have though it could handle ~15,000 rows with decent performance! Works by calcula

I just created a solver for the 4x4 case, also in google sheets... Who would have though it could handle ~15,000 rows with decent performance! Works by calculating via formulae the result of any sequence, 6 moves or less. The bit patterns of each individual move are XORed together for each possible combination of moves. The difference between the current state and the target is calculated, again via XOR, and then looked up in this data sheet via the query functionality, to give the sequence of moves which resulted in that delta bit pattern.