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 A247229 Minimum of the greatest prime factors of (i^prime(n)-1)/(i-1), when i runs through all integers in [2, prime(n)]. 1
 3, 7, 11, 127, 89, 8191, 30839, 363889, 178481, 2089, 4404047, 616318177, 164511353, 2099863, 13264529, 20394401 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If in the definition "greatest" is replaced with "smallest", then we obtain A035095 (see comment there). LINKS FORMULA a(n) == 1 (mod prime(n)). PROG (PARI) a(n) = {mini = 0; p = prime(n); for (i=2, p, f = factor((i^p-1)/(i-1)); gpf = f[#f~, 1]; if (! mini, mini = gpf, mini = min(mini, gpf)); ); mini; } \\ Michel Marcus, Dec 09 2014 CROSSREFS Cf. A035095, A247216. Sequence in context: A287301 A105762 A057469 * A082598 A082599 A354082 Adjacent sequences: A247226 A247227 A247228 * A247230 A247231 A247232 KEYWORD nonn,more AUTHOR Vladimir Shevelev, Nov 27 2014 EXTENSIONS More terms from Peter J. C. Moses, Nov 27 2014 a(13)-a(14) from Michel Marcus, Dec 09 2014 a(15)-a(16) from Jinyuan Wang, Mar 03 2020 STATUS approved

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Last modified March 20 11:53 EDT 2023. Contains 361375 sequences. (Running on oeis4.)