depending on $\chi$..., the critical strip being "$0<\Re(s)<1$".
We found some if for all $n\in\mathbb{N}, \chi(n)=1$,
https://en.wikipedia.org/wiki/Riemann_zeta_function
https://fr.wikipedia.org/wiki/Fonction_z%C3%AAta_de_Riemann#Extension_%C3%A0_%E2%84%82_\_{1}.
Can such an expression be "expre...