User blog comment:Jamazzzzzzzz/Bracket Notation/@comment-37246647-20190517014125

a(4)b is not w^w, it's w^3. Each (3) you add to the expression ADDS another w^2. a(3)(3)b has a FGH ordinal of (w^2)*2. a(3)(3)(3)b is (w^2)*3, a(3)(3)(3)(3)b is (w^2)*4, and so on. By this logic, a(4)b is comparable to w^3, a(n)b is comparable to w^(n-1), and the limit of SBN is w^w.