For $ninmathbb{N}$ we define a double integral begin{equation*} I_n=frac{1}{24}int_0^1int_0^1 frac{-log^3(xy)}{1+xy} (xy(1-xy))^n dxdyend{equation*} We denote $d_n=text{lcm}(1,2,...,n)$ and prove that for all $ninmathbb{N}$, begin{equation*} d_n I_n= 15 (-1)^n 2^{n-4} d_n zeta(5)+(-1)^{n+1} d_n sum_{r=0}^{n} binom{n}{r}left(sum_{k=1}^{n+r} frac{(-1)^{k-1}}{k^5}right) end{equation*} Now if $zeta(5)$ is rational, then $zeta(5)=a/b$, $(a,b)=1$ and $a,binmathbb{N}$. Then we take $ngeq b$ so that $b|d_n$. We show that for all $ngeq 1$, $0