MathNet 2023-part-07 — 187 problems (EN–VI) Question 154

Let $r_{k}$ denote the remainder when $\binom{127}{k}$ is divided by $8$. Compute $r_{1} + 2 r_{2} + 3 r_{3} + \cdots + 63 r_{63}$.

Proposed by: Rishabh Das