Complete the Number Sequence: Finding Missing Terms in 20, 24, 26

To solve the problem of completing the sequence $20, \ldots, 24, 26, \ldots, \ldots$, we recognize the sequence's underlying pattern.

Step 1: Analyze known terms.
The given sequence begins with $20, \ldots, 24, 26, \ldots, \ldots$. Notice the known terms $20$ and $24$, and $26$.

Step 2: Determine the difference between known terms.
The difference between $24$ and $20$ is $4$, suggesting an ongoing pattern.
Between $26$ and $24$, the difference is $2$, proposing alternation in differences or a complete oversight of interspersed terms around $26$.

Step 3: Determine full sequence consistency.
Check if numbers align with a two-step even-number sequence, which implies adding $2$ successively.
Extending forward and back confirms $20, 22, 24, 26, 28, \ldots$.

Step 4: Verification considering other instructions.
The sequence appears to be a straightforward arithmetic one comprising purely even numbers beginning from $20$. This step requires confirming subsequent numbers $28, 30$.

Conclusion: Sequential confirmation proves the arithmetic nature of the understanding, yielding:

$20,22,24,26,28,30$