In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.
['v', 'O', '3161', '929', 'C', 'n', '3521', '5923', 'G', '1529', '7577', '3951', '9141', '2551', '3535', 'L', 'L', '8119']