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A376639 Terms of A151999 which are not a term of A293928.

%I A376639 #15 Nov 15 2024 23:36:49
%S A376639 10,30,34,42,50,60,68,78,90,102,110,114,126,136,150,156,170,180,204,
%T A376639 210,220,222,228,234,250,270,294,300,306,330,340,342,378,390,408,410,
%U A376639 420,438,444,450,456,468,510,514,540,546,550,570,578,582,612,630,654,660,666
%N A376639 Terms of A151999 which are not a term of A293928.
%C A376639 Conjecture: For each a(n) there is no a(n) = A000010(a(k)), k > n.
%C A376639 Conjecture: Every term of A293928 exists in A151999.
%e A376639 10 is a term because 2 divides 4 and 10 and 10 is not a term of A293928.
%e A376639 666 is a term because 666 is a term of A151999 and 666 is not a term of A293928 as it has no totient inverses.
%o A376639 (Sage)
%o A376639 terms = []
%o A376639 for n in range(1, 10000): # Equivalent of A151999/b151999.txt
%o A376639     if euler_phi(n)**2 == euler_phi(euler_phi(n) * n): terms.append(n)
%o A376639 displayTerms = []
%o A376639 for n in range(0,10000):
%o A376639     searchTerms = terms[n+1::]
%o A376639     found = False
%o A376639     for k in range(0, len(searchTerms)):
%o A376639         if terms[n] == euler_phi(searchTerms[k]):
%o A376639             found = True
%o A376639             break
%o A376639     if False == found and n < len(terms):
%o A376639         displayTerms.append(terms[n])
%o A376639 for n in range(0, 55):
%o A376639     print(displayTerms[n], end=', ')
%Y A376639 Cf. A000010, A151999, A293928.
%K A376639 nonn
%O A376639 1,1
%A A376639 _Torlach Rush_, Sep 30 2024