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%I #13 Dec 06 2024 11:31:18
%S 1,2,2,4,2,6,2,8,2,6,2,12,2,6,2,16,2,18,2,12,2,6,2,24,2,6,2,12,2,22,2,
%T 32,2,6,2,36,2,6,2,33,2,18,2,23,2,6,2,48,2,22,2,12,2,54,2,30,2,6,2,50,
%U 2,6,2,64,2,46,2,12,2,22,2,72,2,6,2,12,2,18,2,75
%N Largest m <= n such that phi(m) divides n, where phi is the Euler totient function (A000010).
%H Paolo Xausa, <a href="/A378637/b378637.txt">Table of n, a(n) for n = 1..10000</a>
%F a(2*k+1) = 2, for k >= 1.
%t A378637[n_] := If[OddQ[n] && n > 2, 2, Module[{m = n}, While[!Divisible[n, EulerPhi[m]], m--]; m]];
%t Array[A378637, 100]
%o (PARI) a(n) = my(m=n); while (n % eulerphi(m), m--); m; \\ _Michel Marcus_, Dec 05 2024
%Y Right border of A378636.
%Y Cf. A000010, A319048, A378641.
%K nonn,easy
%O 1,2
%A _Paolo Xausa_, Dec 03 2024