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 A363970 #11 Jun 30 2023 15:37:12
%S A363970 1,1,1,5,1,1,10,5,1,17,1,5,26,10,1,41,1,1,50,21,10,65,1,5,82,26,1,114,
%T A363970 1,17,122,41,1,145,10,5,170,50,26,217,1,10,226,69,1,257,1,41,299,98,1,
%U A363970 354,1,1,362,114,50,401,1,21,442,122,10,525,26,65,530,149,1,602,1,5,626,170
%N A363970 Expansion of Sum_{k>0} k^2 * x^(3*k-2) / (1 - x^(3*k-2)).
%F A363970 a(n) = Sum_{d|n, d==1 mod 3} ((d+2)/3)^2.
%t A363970 a[n_] := DivisorSum[n, ((#+2)/3)^2 &, Mod[#, 3] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Jun 30 2023 *)
%o A363970 (PARI) a(n) = sumdiv(n, d, (d%3==1)*((d+2)/3)^2);
%Y A363970 Cf. A001817, A363901.
%Y A363970 Cf. A103637, A363975.
%K A363970 nonn,easy
%O A363970 1,4
%A A363970 _Seiichi Manyama_, Jun 30 2023