User blog comment:Alemagno12/Terminal Array Hydra/@comment-27014275-20151021062554

Also, the 0th extension is quite obscure. it seems to resolve in n factorial stages, meaning that it only grows at a rate of f[2](n), or so. You should've merged the 0th with the 1st. Universally, this notation doesn't seem to expand much faster than, say, f[w^^3](n). Consider revision.