Question 11
Compute
$$
1 \cdot 2^{2} + 2 \cdot 3^{2} + 3 \cdot 4^{2} + \cdots + 19 \cdot 20^{2}
$$
$$
1 \cdot 2^{2} + 2 \cdot 3^{2} + 3 \cdot 4^{2} + \cdots + 19 \cdot 20^{2}
$$
MathNet 2009-part-05 — 172 problems (EN–VI) Question 11
Math Olympiad Vault · MathNet 2009-part-05 — 172 problems (EN–VI)