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%I #20 Mar 30 2023 02:32:20
%S 2,7,29,19,641,41,541,1597,22993,397,5521,303293,380881,25117,
%T 210466621,508771,1573071713,108991369171,1343341,2724783836059,
%U 39558401,2525293,4807441,215038823,1173553,61001,16463734208221,3813697527769,58116853330557841,327866809,99901
%N a(n) is the largest prime factor of 2^n + 5^n.
%H Amiram Eldar, <a href="/A337429/b337429.txt">Table of n, a(n) for n = 0..387</a> (terms 0..200 from Hugo Pfoertner)
%F a(n) = A006530(A074600(n)).
%t a[n_] := FactorInteger[2^n + 5^n][[-1, 1]]; Array[a, 31, 0] (* _Amiram Eldar_, Mar 30 2023 *)
%o (PARI) for(n=0,30,my(p=2^n+5^n);print1(vecmax(factor(p)[,1]),", "))
%Y Cf. A006530, A074600, A094474, A094475, A122118.
%K nonn
%O 0,1
%A _Hugo Pfoertner_, Sep 23 2020