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%I #17 Apr 04 2023 07:42:07
%S 484,968,1100,2116,3364,4232,6084,6724,6728,8464,10404,11132,11236,
%T 13448,16928,19044,22472,26896,27556,29584,31684,36100,44944,51076,
%U 53792,55112,56644,59168,63368,65824,67416,68644,72200,79524,80344,89888,96100,99856,102152,107584
%N Nontotients (A005277) that are the product of two totients (A002202).
%C We can have a list of nontotients and their factorizations into two totients. A totient m is in A301587 if and only if m never occurs in this list as a divisor of the nontotients. Using the list, many totients (10, 22, 44, 46, ...) are ruled out of A301587. But generally it's hard to prove that a number is in A301587.
%H Jianing Song, <a href="/A329872/b329872.txt">Table of n, a(n) for n = 1..7280</a> (All terms <= 10^8)
%H Jianing Song, <a href="/A329872/a329872.txt">Nontotients, and their factorizations into two totients</a>
%e 484 is here, because 484 = 22*22, and 22 is a totient while 484 isn't. Similarly, if p == 3 (mod 4) is a prime such that (p-1)^2+1 is composite, then (p-1)^2 is here.
%o (PARI) isA329872(n) = if(!istotient(n), my(v=divisors(n)); for(i=1, (1+#v)\2, if(istotient(v[i])&&istotient(n/v[i]), return(1))); 0); \\ improved by _Jinyuan Wang_, Mar 25 2023
%Y Cf. A002202, A005277, A301587.
%Y Squares of terms of A281187 are terms of this sequence.
%K nonn
%O 1,1
%A _Jianing Song_, Nov 23 2019
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