I see two sequences alternate. After separating, one sequence is+ + + . . . + (1) Another sequence is + + + . . . + (2) Sequence (1), after reducing, is the sum of = 52 equal addends, each of which is , so this sum is . Sequence (2), after reducing, is the sum of = 52 equal addends, each of which is , so this sum is . Therefore, the total sum is + = + = = = 16 = 16 . ANSWER