Question 149
Prove the identity
$$
\sum_{d \mid n} \tau(d)^{3}=\left(\sum_{d \mid n} \tau(d)\right)^{2}
$$
$$
\sum_{d \mid n} \tau(d)^{3}=\left(\sum_{d \mid n} \tau(d)\right)^{2}
$$
MathNet 2007-part-03 — 185 problems (EN–VI) Question 149
Math Olympiad Vault · MathNet 2007-part-03 — 185 problems (EN–VI)