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PROJECT EULER · #0518

Prime Triples and Geometric Sequences

Statement only · SolvedOriginal problem ↗

Let S(n)=a+b+c over all triples (a,b,c) such that:

  • a, b and c are prime numbers.
  • a<b<c<n.
  • a+1, b+1, and c+1 form a geometric sequence.

For example, S(100)=1035 with the following triples:

(2,5,11), (2,11,47), (5,11,23), (5,17,53), (7,11,17), (7,23,71), (11,23,47), (17,23,31), (17,41,97), (31,47,71), (71,83,97)

Find S(108).

Write-up coming later

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