User blog comment:MilkyWay90/Extension to the Up-Arrow Notation/@comment-32697988-20180602232754

F(3,3,a)~f_w(a) F(3,3,a,2)=F(3,3,F(3,3,a,1))~f^2_w(a) F(3,3,a,3)~f^3_w(a) F(3,3,a,a)~f_{w+1}(a) F(3,3,a,a,2)~F(3,3,a,F(3,3,a,a))~f^2_{w+1}(a) F(3,3,a,a,a)~f_{w+2}(a)

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So this has growth rate ω×2 in FGH.