Given 2 contracted arrays in the form :
{times, number, times, number .... ]
multiply these array expanding them. Example:
[1,2,2,4] is equivalent to [2, 4, 4]
and
[2,1,1,4] is equivalent to [1, 1, 4]
the result would be [(1x2), (1x4), (4x4)] = [2, 4, 16]