Find the incorrect term in the following number series. Series: 2, 3, 4, 4, 6, 8, 9, 12, 16

Introduction / Context:
The series is formed by interweaving three independent doubling chains starting from 2, 3, and 4. Identifying these strands shows which value is inconsistent.

Given Data / Assumptions:

• Overall sequence: 2, 3, 4, 4, 6, 8, 9, 12, 16
• We expect three strands: start values 2, 3, 4; each subsequent appearance of a strand doubles its previous value.

Concept / Approach:
Track positions modulo 3 to separate strands: S1: 2 → 4 → 8 → 16; S2: 3 → 6 → 12; S3: 4 → 8 → 16. Any term not equal to the correct doubling for its strand is wrong.

Step-by-Step Solution:
Positions 1, 4, 7: S1 should be 2, 4, 8; the sequence shows 2, 4, 9 (incorrect; should be 8). Positions 2, 5, 8: S2 is 3, 6, 12 (correct). Positions 3, 6, 9: S3 is 4, 8, 16 (correct).

Verification / Alternative check:
Replacing 9 by 8 restores perfect doubling for S1 and yields consistent triplets.

Why Other Options Are Wrong:
3, 6, 12 are all correct members of strand S2 and therefore not the misfit.

Common Pitfalls:
Treating the entire list as one sequence instead of three interleaved doubling sequences.

Final Answer:
9