Let $a,b,c>1$, $a^{3},b^{3}$ and $c^{3}$ be in A.P., and $\log_{a} b,\ \log_{c} a$ and $\log_{b} c$ be in G.P. If the sum of first $20$ terms of an A.P., whose first term is $\dfrac{a+4b+c}{3}$ and the common difference is $\dfrac{a-8b+c}{10}$, is $-444$, then $abc$ is equal to: