We consider the behavior of the power series $𝔐_0(z) = ∑_{n=1}^{∞} μ^2(n)z^n$ as z tends to $e(β) = e^{2πiβ}$ along a radius of the unit circle. If β is irrational with irrationality exponent 2 then $𝔐_0(e(β)r) = O((1-r)^{-1/2-ε})$. Also we consider the cases of higher irrationality exponent. We prove that for each δ there exist irrational numbers β such that $𝔐_0(e(β)r) = Ω((1-r)^{-1+δ})$.