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 A109347 Zsigmondy numbers for a = 5, b = 3: Zs(n, 5, 3) is the greatest divisor of 5^n - 3^n (A005058) that is relatively prime to 5^m - 3^m for all positive integers m < n. 9
 2, 1, 49, 17, 1441, 19, 37969, 353, 19729, 421, 24325489, 481, 609554401, 10039, 216001, 198593, 381405156481, 12979, 9536162033329, 288961, 18306583, 6125659, 5960417405949649, 346561, 103408180634401, 152787181, 3853528045489, 179655841, 93132223146359169121 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Eric Weisstein's World of Mathematics, Zsigmondy's Theorem PROG (PARI) rad(n) = factorback(factor(n)[, 1]) lista(nn) = {prad = 1; for (n=1, nn, val = 5^n-3^n; d = divisors(val); gd = 1; forstep(k=#d, 1, -1, if (gcd(d[k], prad) == 1, g = d[k]; break)); print1(g, ", "); prad = ra(prad*val); ); } \\ Michel Marcus, Nov 15 2016 CROSSREFS Cf. A064078, A064079, A064080, A064081, A064082, A064083, A109325, A109348, A109349. Sequence in context: A214221 A100018 A255856 * A054210 A225778 A271442 Adjacent sequences:  A109344 A109345 A109346 * A109348 A109349 A109350 KEYWORD nonn AUTHOR Jonathan Vos Post, Aug 21 2005 EXTENSIONS Edited, corrected and extended by Ray Chandler, Aug 26 2005 Definition corrected by Jerry Metzger, Nov 04 2009 More terms from Michel Marcus, Nov 14 2016 STATUS approved

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Last modified August 8 04:32 EDT 2020. Contains 336290 sequences. (Running on oeis4.)