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%I #19 Oct 23 2019 10:05:35
%S 1,2,4,6,10,14,15,18,21,22,26,33,34,35,38,39,45,46,50,51,54,55,57,58,
%T 62,65,69,74,75,77,82,85,86,87,91,93,94,95,98,99,106,111,115,118,119,
%U 122,123,129,133,134,135,141,142,143,145,146,147,153,155,158,159,161,162,166,175,177
%N Numbers n such that A258409(n) * A002322(n) = A000010(n), where A258409(1) = 1.
%C Squarefree terms > 2 give A006881.
%C Even terms are even terms of A033948.
%C No terms of the form p^k > 4, where p is a prime.
%C The sequence has natural density 0. - Information from Carl Pomerance, Jan 09 2017
%H Amiram Eldar, <a href="/A280862/b280862.txt">Table of n, a(n) for n = 1..10000</a>
%t {1}~Join~Select[Range@ 180, (GCD @@ (Divisors[#] - 1)) CarmichaelLambda@ # == EulerPhi@ # &] (* _Michael De Vlieger_, Jan 10 2017 *)
%o (PARI) a258409(n) = if(n%2==0, return(1)); if(n%3==0, return(2)); if(n%5==0 && n%4 != 1, return(2)); gcd(apply(p->p-1, factor(n)[, 1]));
%o a002322(n) = lcm(znstar(n)[2]);
%o is(n) = a258409(n) * a002322(n) == eulerphi(n);
%Y Cf. A000010, A002322, A006881, A033948, A258409.
%K nonn
%O 1,2
%A _Thomas Ordowski_ and _Altug Alkan_, Jan 09 2017
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