Thanks for the query.
The series is comprised of two separate ones with the odd members and even members in different series.
The odd numbered members 16, 15, 13, 10, 6 is decreasing with a difference of -(d + 1), where d = 0 i.e., the common difference is -1, -2, -3 and so on.
The even numbered members 2, 4, 7, 11 are increasing with a difference of (d + 1), where d = 1 i.e., the common difference is 2, 3, 4, etc
Hence the 10th member of the series should be 11 + (4 +1) = 16
