%I #7 Jul 12 2022 20:59:34
%S 0,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,
%T 1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,
%U 1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1
%N a(n) = 1 if n is odd and phi(x) = n^2 + 1 has no solutions, otherwise 0.
%H Antti Karttunen, <a href="/A355450/b355450.txt">Table of n, a(n) for n = 1..100000</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = A355451(1 + n^2).
%o (PARI)
%o A355451(n) = (!(n%2) && !istotient(n));
%o A355450(n) = A355451(1+(n^2));
%Y Characteristic function of A106571.
%Y Cf. A355451.
%K nonn
%O 1
%A _Antti Karttunen_, Jul 12 2022
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