Largest pairwise-coprime subset sum

Consider subsets of S={1,2,3,,30}S = \{1, 2, 3, \dots, 30\} in which every pair of elements is coprime. Among all such subsets, find the one whose elements have the largest possible sum, and give that sum.

Show hints (2)+
  1. 11 is free; each prime 30\le30 may divide at most one chosen number. Prefer large prime powers.
  2. {1,11,13,17,19,23,25,27,28,29}\{1,11,13,17,19,23,25,27,28,29\} - with 27,25,2827,25,28 monopolizing 3,5,2,73,5,2,7 - sums to 193193.

Answer

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193

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Asked at: Jane Street, SIG

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