olymmath

TSTST 2024 Problem 3

    Let A={a1,…,a2024}A = \{a_{1},\ldots ,a_{2024}\} be a set of 2024 pairwise distinct real numbers. Assume that there exist positive integers b1,b2,…,b2024b_{1},b_{2},\ldots ,b_{2024} such that

    a1b1+a2b2+⋅⋅⋅+a2024b2024=0.a_{1}b_{1} + a_{2}b_{2} + \cdot \cdot \cdot +a_{2024}b_{2024} = 0.

    Prove that one can choose a2025,a2026,a2027,…a_{2025},a_{2026},a_{2027},\ldots such that ak∈Aa_{k}\in A for all k≥2025k\geq 2025 and, for every positive integer dd , there exist infinitely many positive integers nn satisfying

    ∑k=1nakkd=0.\sum_{k = 1}^{n}a_{k}k^{d} = 0.

    Dataset text NuminaMath olympiads. Quoted with source.

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