Definition: In this task, you are given inputs i, j, and A, where i and j are integers and A is a list. You need to find all elements of A from the ith element to the jth element, reverse the order in which they occur, and then concatenate them to output the resultant 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 concatenate the elements and then reverse the string.
Input: 6, 20, ['W', '6757', '409', 'A', '763', '2875', '6447', '6617', '8919', '8987', '2301', '7977', '781', '9509', 'v', '8299', 'z', '7865', '9583', '4857']

485795837865z8299v95097817977230189878919661764472875