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 $\frac{a + 4b + c}{3}$ and the common difference is $\frac{a - 8b + c}{10}$ is -444 , then $abc$ is equal to