User blog comment:QuasarBooster/Second-order worms ordinal analysis dump/@comment-36984051-20190620230843/@comment-35470197-20190621010408

Also, φ(n+1,0) is obtained as the limit φ(n,φ(n,…φ(n,0)…)), and φ(n+1,a+1) is obtained as the limit φ(n,φ(n,…φ(n,φ(n+1,a)+1)…)). (You might know them, though.)