User blog comment:Alemagno12/A ordinal notation/@comment-11227630-20150721045807/@comment-25601061-20150723180733

Sorry, that was me. I'm still new at LaTeX.

Anyways, $$A(0, /alpha ) = /sup (A(0, /alpha [1]), A(0, /alpha [2]), A(0, /alpha [3]),...)$$