A(1, 2) is a mathematical notation that typically represents a specific value or function in the context of combinatorics or sequences. In this case, it can refer to the first element of a sequence or a function evaluated at the coordinates (1, 2). In combinatorial contexts, A(1, 2) might denote the number of ways to choose 1 item from a set of 2 items, which is simply 2. This notation is often used in discussions involving combinations, permutations, or mathematical functions.