This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A364064 #21 Jul 06 2023 08:00:15
%S A364064 1,3,4,5,6,9,8,9,10,16,12,13,14,21,16,17,21,26,20,21,22,31,24,32,26,
%T A364064 36,28,29,30,41,40,33,34,50,36,37,38,60,40,41,42,56,44,54,56,61,48,49,
%U A364064 50,66,52,64,54,81,56,57,63,76,72,61,62,81,64,76,66,99,68,69,70,102,72,73,88,108,76,77,78,101
%N A364064 Expansion of Sum_{k>0} k * x^k / (1 - x^(3*k-2)).
%H A364064 Seiichi Manyama, <a href="/A364064/b364064.txt">Table of n, a(n) for n = 1..10000</a>
%F A364064 a(n) = (1/3) * Sum_{d | 3*n-2, d==1 (mod 3)} (d+2).
%F A364064 G.f.: Sum_{k>0} x^k / (1 - x^(3*k-2))^2.
%t A364064 a[n_] := DivisorSum[3*n - 2, # + 2 &, Mod[#, 3] == 1 &]/3; Array[a, 100] (* _Amiram Eldar_, Jul 05 2023 *)
%o A364064 (PARI) a(n) = sumdiv(3*n-2, d, (d%3==1)*(d+2))/3;
%Y A364064 Cf. A359212, A363889.
%K A364064 nonn
%O A364064 1,2
%A A364064 _Seiichi Manyama_, Jul 04 2023