In this task, you are given inputs 'i', 'j', and A, where 'i' and 'j' are integers and A is a list. A list is shown by two brackets and comma-separated numbers and characters inside, like ['1', '12', 'l']. You need to concatenate all elements of A from the ith element to the jth element, and then reverse the resulting string. 'i' and 'j' will be non-negative, and will always have a value less than the length of A. 'i' will always be less than 'j'. Perform the operations in order, i.e., do not reverse first and then concatenate.
20, 21, ['3335', '9721', '8247', 'X', 'A', '1593', '8051', 'x', 'M', 'n', '8817', 'I', 'j', '9787', 'V', 'L', '7075', '9883', '7383', '4943', 'o', '7507', '3307', 'R']