Find the missing term: 2, 1, 2, 4, 4, 5, 6, 7, 8, 8, 10, 11, ?

9
10
11
12

The missing term is 12.

The sequence is a combination of two sequences: 2, 4, 6, 8, 10, 12… and 1, 2, 3, 4, 5, 6…

The first sequence is a list of even numbers, starting with 2 and increasing by 2 each time.

The second sequence is a list of natural numbers, starting with 1 and increasing by 1 each time.

The two sequences are alternated, with the first term of the first sequence followed by the first term of the second sequence, and so on.

Therefore, the missing term is 12, which is the next even number after 10.