The expression for the $n$-th term of the sequence is $4n + 7$.

To find the first three terms of the sequence, we substitute $n = 1$, $n = 2$, and $n = 3$ respectively:

1. For $n = 1$: $4(1) + 7 = 4 + 7 = 11$

2. For $n = 2$: $4(2) + 7 = 8 + 7 = 15$

3. For $n = 3$: $4(3) + 7 = 12 + 7 = 19$

Thus, the first three terms of the sequence are 11, 15, and 19, respectively.

If you need further details or have any questions, please let me know! Here are some related questions you might consider:

1. How would you find the 10th term of this sequence?
2. What would be the sum of the first 20 terms of this sequence?
3. Can you generate a formula for the sum of the first $n$ terms of this sequence?
4. How would you determine if a given number is a term in this sequence?
5. What happens to the sequence terms as $n$ becomes very large?

Tip: Understanding the sequence formula $4n + 7$ can help in analyzing patterns and predicting future terms, which is useful in both pure and applied mathematics.