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%I #10 May 18 2022 03:15:20
%S 1,0,0,0,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,0,0,1,0,0,
%T 0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,0,0,1,
%U 0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0
%N a(n) = 1 if n-phi(n) is a multiple of 4, otherwise 0.
%H Antti Karttunen, <a href="/A354097/b354097.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = 1 iff A010873(A051953(n)) == 0.
%t a[n_] := If[Divisible[n - EulerPhi[n], 4] , 1, 0]; Array[a, 100] (* _Amiram Eldar_, May 17 2022 *)
%o (PARI) A354097(n) = (0==((n-eulerphi(n))%4));
%Y Characteristic function of A354098.
%Y Cf. A000010, A010873, A051953.
%Y Cf. also A354037.
%K nonn
%O 1
%A _Antti Karttunen_, May 17 2022