Let \( f(x) = x^6 + 2x^4 + x^3 + 2x + 3, \ x \in \mathbb{R} \). Then the natural number \( n \) for which \( \displaystyle \lim_{x \to 1} \dfrac{x^n f(1) - f(x)}{x - 1} = 44 \) is: