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%I #19 Sep 08 2022 08:46:17
%S 5,7,43,37,311,43,55987,1297,2467,311,3154757,97,760891,55987,1201,
%T 98801,30839,46441,638073026189,6781,1822428931,51828151,7505944891,
%U 1678321,40185601,760891,623067280651,5030761,7369130657357778596659,1950271,49744740983476472807
%N Largest prime factor of 6^n - 1.
%H Amiram Eldar, <a href="/A274907/b274907.txt">Table of n, a(n) for n = 1..420</a> (terms 1..100 from Vincenzo Librandi)
%H J. Brillhart et al., <a href="http://dx.doi.org/10.1090/conm/022">Factorizations of b^n +- 1</a>, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
%F a(n) = A006530(A024062(n)). - _Michel Marcus_, Jul 11 2016
%e 6^5 - 1 = 7775 = 5*5*311, so a(5) = 311.
%t Table[FactorInteger[6^n - 1][[-1, 1]], {n, 40}]
%o (Magma) [Maximum(PrimeDivisors(6^n-1)): n in [1..40]];
%o (PARI) a(n) = vecmax(factor(6^n-1)[,1]); \\ _Michel Marcus_, Jul 13 2016
%Y Cf. A006530, A024062.
%Y Cf. similar sequences listed in A274906.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Jul 11 2016
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