I have found two contradicting statements about the value of $\zeta(k)$ when $k=2n+1$ and $n\in\mathbb{Z_0^+}$. Which one is correct?
"The Riemann zeta function for odd integers has no known closed-form formula", that is, you can't find $\zeta(k)=f(k)$ such that $f$ holds for all positive odd integers. This is apparently a "well-known" fact.
Wikipedia states here that $\zeta(k)$ can be expressed for all positive integers, even or odd, using the formula:
$\zeta(k)=\frac{2^k}{2^k-1}+\sum_{r=2}^\infty\frac{(p_{r-1}\#)^k}{J_k(p_r\#)}\quad(k=2,3,\dots)$
which involves primorials and the Jordan totient function.
EDIT: I understand the above is not a closed formula. But then what about this paper, which proposes an explicit closed-form formula?
The paper you link to proposes "closed forms" of the type
$$\zeta(3)=\frac{2^3}{2^3-1}\beta(3)-\dots$$
with
$$\beta(s)=\sum_{k=1}^\infty\frac{(-1)^{k-1}}{(2k-1)^s}$$
Thus the infinite term is just hidden away in the function $\beta$ (which occurs in every expression they give) and the claim of having obtained closed forms is a tall one indeed.