User blog comment:Edwin Shade/How To Become Number One On The Leaderboard/@comment-32783837-20180102204148/@comment-28606698-20180109203249

May be Fish is the third, but I remember unlike FOOT-function the community doubted whether Fish's notation  is significantly stronger than Rayo's one. Anyway I can't judj about it since I do not enough know about uncomputable functions.