We assume that, for all $k\in\mathbb{N}$, $p_k=\frac{1}{2^{k+1}}$.
Verify that, for all $t\in\left[0,1\left[$, $\varphi_n(t)\neq 1$.
We assume that, for all $k\in\mathbb{N}$, $p_k=\frac{1}{2^{k+1}}$.

Verify that, for all $t\in\left[0,1\left[$, $\varphi_n(t)\neq 1$.