A) \( \Large \frac{1}{2}n \left(n+1\right) \) |
B) \( \Large \frac{1}{6}n \left(2n+1\right) \) |
C) \( \Large \frac{1}{6} \left(n+1\right) \left(2n+1\right) \) |
D) \( \Large \frac{1}{6}n \left(n+1\right) \) |
B) \( \Large \frac{1}{6}n \left(2n+1\right) \) |