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A284104 a(n) = Sum_{d|n, d == 5 (mod 6)} d.

%I A284104 #22 Nov 26 2023 03:06:16
%S A284104 0,0,0,0,5,0,0,0,0,5,11,0,0,0,5,0,17,0,0,5,0,11,23,0,5,0,0,0,29,5,0,0,
%T A284104 11,17,40,0,0,0,0,5,41,0,0,11,5,23,47,0,0,5,17,0,53,0,16,0,0,29,59,5,
%U A284104 0,0,0,0,70,11,0,17,23,40,71,0,0,0,5,0,88,0,0,5
%N A284104 a(n) = Sum_{d|n, d == 5 (mod 6)} d.
%H A284104 Seiichi Manyama, <a href="/A284104/b284104.txt">Table of n, a(n) for n = 1..10000</a>
%F A284104 G.f.: Sum_{k>=1} (6*k - 1)*x^(6*k-1)/(1 - x^(6*k-1)). - _Ilya Gutkovskiy_, Mar 21 2017
%F A284104 Sum_{k=1..n} a(k) = c * n^2 + O(n*log(n)), where c = Pi^2/72 = 0.137077... (A086729). - _Amiram Eldar_, Nov 26 2023
%t A284104 Table[Sum[If[Mod[d, 6] == 5, d, 0], {d, Divisors[n]}], {n, 80}] (* _Indranil Ghosh_, Mar 21 2017 *)
%t A284104 Table[Total[Select[Divisors[n],Mod[#,6]==5&]],{n,80}] (* _Harvey P. Dale_, Dec 30 2017 *)
%o A284104 (PARI) for(n=1, 80, print1(sumdiv(n, d, if(Mod(d,6)==5, d, 0)),", ")) \\ _Indranil Ghosh_, Mar 21 2017
%o A284104 (Python)
%o A284104 from sympy import divisors
%o A284104 def a(n): return sum([d for d in divisors(n) if d%6==5]) # _Indranil Ghosh_, Mar 21 2017
%Y A284104 Cf. A086729, A109702.
%Y A284104 Cf. Sum_{d|n, d=k-1 mod k} d: A000593 (k=2), A078182 (k=3), A050452 (k=4), A284103 (k=5), this sequence (k=6), A284105 (k=7).
%K A284104 nonn,easy
%O A284104 1,5
%A A284104 _Seiichi Manyama_, Mar 20 2017