The terms a_0, a_1, and a_2 are often used in mathematics and computer science to represent specific elements in a sequence or series. In a typical sequence, a_0 denotes the first element, a_1 the second, and a_2 the third. These notations help in organizing and referencing elements systematically. In programming, these variables can represent values in an array or list. For example, in an array called A, A[0] would correspond to a_0, A[1] to a_1, and A[2] to a_2. This structure allows for efficient data manipulation and retrieval.