User blog comment:QuasarBooster/Extra-Growth Hierarchy, extension of FGH/@comment-25337554-20150620101151/@comment-24923514-20150620162937

I do admit, ordinal expansions like those are tricky to get used to. $$\text{Ex}_{0,\omega2}(1)$$ expands to $$\text{Ex}_{0,\omega+\omega}(1)$$, so first you're really just evaluating one omega first. The omega gets added to the previous entry, and is then replaced where it originally was with $$\text{Ex}_{0,\omega+1}(1)$$, where the +1 comes from replacing where the omega was with n.