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a(n) = gcd(A326127(n), A326128(n)).
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%I #20 Jul 29 2020 16:37:56

%S 1,1,2,1,4,0,6,1,1,2,10,1,12,4,6,1,16,1,18,1,10,8,22,6,1,10,2,21,28,

%T 12,30,1,18,14,22,1,36,16,22,10,40,12,42,1,4,20,46,1,1,1,30,3,52,12,

%U 38,2,34,26,58,3,60,28,2,1,46,12,66,1,42,4,70,1,72,34,2,3,58,12,78,1,1,38,82,7,62,40,54,2,88,2,70,1,58,44,70,30

%N a(n) = gcd(A326127(n), A326128(n)).

%C Question: Are there any other numbers than those in A000396 that satisfy a(k) = A326128(k)?

%C See also comments in A336641, where all such k should reside. - _Antti Karttunen_, Jul 29 2020

%H Antti Karttunen, <a href="/A326129/b326129.txt">Table of n, a(n) for n = 1..20000</a>

%F a(n) = n - A336645(n). - _Antti Karttunen_, Jul 29 2020

%o (PARI)

%o A326127(n) = (sigma(n)-core(n)-n);

%o A326128(n) = (n-core(n));

%o A326129(n) = gcd(A326127(n), A326128(n));

%Y Cf. A000396, A007913, A326126, A326127, A326128.

%Y Cf. also A009194, A325385, A325813, A325975, A326046, A326047, A326048, A326056, A326057, A326060, A326062, A326130, A326140, A326144, A336641, A336645.

%K nonn

%O 1,3

%A _Antti Karttunen_, Jun 09 2019