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.
['s', 'H', '5513', '6551', 'L', 'H', '4463', '6663', 'N', 'g', '8201', 'U', 'D', '1329', '195', 'S', 'H', 'w', 'k', 'T']