A single repetition of the wave is misleading. For N repetitions of the wave you need N + 1 buttresses not 2 N.
Also, while brick is stronger in compression a buttress increases toppling resistance in both directions so you need to consider material properties not just the geometry.
But the math depends so strongly on how often the buttresses are needed, and the length of the buttresses, so you can't assume those things. The goal is a wall of equivalent strength, after all. If equivalent strength needs slightly less distance, or slightly smaller buttresses, the result could be thrown completely off in either direction.
