User blog comment:Edwin Shade/There is No Limit To Googology/@comment-80.98.179.160-20171123100714/@comment-80.98.179.160-20171123111233

$$E_{\alpha+1}(a)=E_\alpha^{E_\alpha^{E_\alpha(a)}(a)}(a)$$.

$$E_\alpha(n)=E_{\alpha[E_{\alpha[n]}(n)]}(n)$$, iff α is a limit ordinal.

It may or may not beat FOOT function or even Rayo, but can beat Xi, the fake record-holder.

The first E number is $$E_\omega(10^{100})$$, may or may not surpass BIG FOOT.