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Numbers n > 2 such that A258409(n)*A002322(n) divides n-1.
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%I #10 Jun 26 2019 10:59:28

%S 1729,41041,75361,172081,449065,656601,670033,1050985,2433601,2704801,

%T 3664585,4903921,6840001,7995169,8355841,8719921,9582145,9613297,

%U 9890881,10402561,11205601,12945745,13992265,15888313,16778881,17586361,17812081,19683001,20964961

%N Numbers n > 2 such that A258409(n)*A002322(n) divides n-1.

%C A proper subset of the Carmichael numbers A002997.

%C If n is in the sequence, then n-1 is not squarefree.

%C Problem: are there infinitely many such numbers?

%H Amiram Eldar, <a href="/A284671/b284671.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[3, 10^6], Divisible[#-1, CarmichaelLambda[#] * GCD @@ (Divisors[#] - 1)] &] (* _Amiram Eldar_, Jun 26 2019 *)

%Y Cf. A002322, A002997, A258409.

%K nonn

%O 1,1

%A _Thomas Ordowski_ and _Altug Alkan_, Apr 01 2017