This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A359685 #18 Mar 30 2023 02:31:08 %S A359685 3,3,11,5,37,7,5,11,521,47,71,79,547,911,32783,241,307,6899,24967, %T A359685 87383,457,4799,270601,7109,3728273,12497,1201,100613,2017,17318417, %U A359685 859,87211,47491,8589934609,195329,1483453,320370521,8191129,549755813927,478881371 %N A359685 Greatest prime dividing 2^n + n. %H A359685 Amiram Eldar, <a href="/A359685/b359685.txt">Table of n, a(n) for n = 1..406</a> %F A359685 a(n) = A006530(A006127(n)). %p A359685 a:= n-> max(numtheory[factorset](2^n+n)): %p A359685 seq(a(n), n=1..40); # _Alois P. Heinz_, Jan 11 2023 %t A359685 a[n_] := FactorInteger[2^n + n][[-1, 1]]; Array[a, 40] (* _Amiram Eldar_, Mar 30 2023 *) %o A359685 (PARI) a(n) = vecmax(factor(2^n+n)[,1]); \\ _Michel Marcus_, Jan 11 2023 %o A359685 (Python) %o A359685 from sympy import primefactors %o A359685 def A359685(n): return max(primefactors((1<<n)+n)) # _Chai Wah Wu_, Jan 11 2023 %Y A359685 Cf. A000040, A006127, A006530. %K A359685 nonn %O A359685 1,1 %A A359685 _Philippe Deléham_, Jan 11 2023