User blog comment:Wythagoras/Dollar function formal definition/@comment-5150073-20130629110623/@comment-5529393-20130630013019

Oh wait, actually psi_I (I^2 a + I b + c) is larger than lambda_a (b, c) since you have lambda_{a+1} (1) = lambda_a (Omega_Omega_Omega...) whereas psi_I (I^2 (a+1)) is the first ordinal satisfying psi_I (I^2 a + I x) = x, which will be much larger.