Answer:
3, 12, 27, 48
Explanation:
To find the first 4 terms substitute n = 1, 2, 3, 4 into the rule, that is
n = 1 → 3 × 1² = 3 × 1 = 3 ← first term
n = 2 → 3 × 2² = 3 × 4 = 12 ← second term
n = 3 → 3 × 3² = 3 × 9 = 27 ← third term
n = 4 → 3 × 4² = 3 × 16 = 48 ← fourth term