Write the first 6 unique elements that will be generated by the following recursive definition for set A. Do not take the basis element as the first element, give 6 elements that are obtained using the basis element. Assume that the string concatenations shown in the recursive step will be performed to obtain the new elements of A.

Consider 1, 2, a, and b to be strings.

Consider w and x to be placeholders for strings.

(i) Basis: [1, 2] A

(ii) Recursive step: If [w, x] A, then [wa, xa] A and [wb, xb] A

(iii) Closure: Set A consists of exactly the elements that can be obtained by starting with the basis elements of A and applying the recursive step finitely many times to construct the elements of A.