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same size same sum

Source: KJMO 2023 P7

November 4, 2023
number theory

Problem Statement

Find the smallest positive integer NN such that there are no different sets A,BA, B that satisfy the following conditions. (Here, NN is not a power of 22. That is, N1,21,22,N \neq 1, 2^1, 2^2, \dots.)
[*] A,B{1,21,22,23,,22023}{N}A, B \subseteq \{1, 2^1, 2^2, 2^3, \dots, 2^{2023}\} \cup \{ N \} [*] A=B1|A| = |B| \geq 1 [*] Sum of elements in AA and sum of elements in BB are equal.