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a(n) = 1 if n and sigma(n) are relatively prime, 0 otherwise, where sigma(n) = sum of divisors of n, A000203; Characteristic function of A014567.
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%I #6 May 30 2019 09:43:53

%S 1,1,1,1,1,0,1,1,1,0,1,0,1,0,0,1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,1,0,0,

%T 1,1,1,0,1,0,1,0,1,0,0,0,1,0,1,1,0,0,1,0,1,0,1,0,1,0,1,0,1,1,1,0,1,0,

%U 0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,0,0,1,0,0,0,1,1,0,1,1,0,1,0,0

%N a(n) = 1 if n and sigma(n) are relatively prime, 0 otherwise, where sigma(n) = sum of divisors of n, A000203; Characteristic function of A014567.

%H Antti Karttunen, <a href="/A325964/b325964.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%F a(n) = 1 if gcd(n, sigma(n)) [= A009194(n)] is 1, 0 otherwise.

%o (PARI) A325964(n) = (1==gcd(n,sigma(n)));

%Y Cf. A000203, A009194, A014567.

%Y Cf. also A297086, A322980.

%K nonn

%O 1

%A _Antti Karttunen_, May 29 2019