User blog comment:Angrybirdstd/Crispin/@comment-32783837-20180202024541/@comment-32783837-20180204143408

I use "powten" as it is defined in Hypercalc, where xPTy is Ex#y in Hyper-E. Since there is no X, I assume that the unary PT(y) = 10↑↑y.