DISPROVED
This has been solved in the negative.
Let $a_1<a_2<\cdots $ be an infinite sequence of integers such that $a_{i+1}/a_i\to 1$. If every arithmetic progression contains infinitely many integers which are the sum of distinct $a_i$ then every sufficiently large integer is the sum of distinct $a_i$.
This was disproved by Cassels
[Ca60].
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T. F. Bloom, Erdős Problem #253, https://www.erdosproblems.com/253, accessed 2026-01-16