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%I #7 Jun 02 2019 00:52:26
%S 0,1,0,5,0,5,0,13,10,7,0,21,0,9,8,29,0,32,0,31,10,13,0,53,26,15,36,29,
%T 0,41,0,61,14,19,12,85,0,21,16,79,0,53,0,61,62,25,0,117,50,83,20,71,0,
%U 113,16,105,22,31,0,137,0,33,82,125,18,77,0,91,26,73,0,188,0,39,108,101,18,89,0,175,118,43,0,181,22
%N a(n) is the largest k <= sigma(n)-A007947(n) such that n-k and n-(sigma(n)-k) are relatively prime.
%H Antti Karttunen, <a href="/A325972/b325972.txt">Table of n, a(n) for n = 1..20000</a>
%H Antti Karttunen, <a href="/A325972/a325972.txt">Data supplement: n, a(n) computed for n = 1..65537</a>
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F a(n) = A000203(n) - A325971(n).
%o (PARI)
%o A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947
%o A325972(n) = { my(s=sigma(n)); forstep(i=s-A007947(n), 0, -1, if(1==gcd(n-i, n-(s-i)), return(i))); };
%Y Cf. A000203, A007947, A324213, A325818, A325962, A325966, A325970, A325971.
%K nonn
%O 1,4
%A _Antti Karttunen_, May 31 2019
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