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 A103638 #11 Jun 30 2023 12:45:34
%S A103638 0,4,0,4,25,4,0,68,0,29,121,4,0,200,25,68,289,4,0,429,0,125,529,68,25,
%T A103638 680,0,200,841,29,0,1092,121,293,1250,4,0,1448,0,493,1681,200,0,2061,
%U A103638 25,533,2209,68,0,2529,289,680,2809,4,146,3400,0,845,3481,429,0,3848
%N A103638 a(n) = Sum_{d|n, d==2 mod 3} d^2.
%H A103638 Seiichi Manyama, <a href="/A103638/b103638.txt">Table of n, a(n) for n = 1..10000</a>
%t A103638 a[n_] := DivisorSum[n, #^2 &, Mod[#, 3] == 2 &]; Array[a, 100] (* _Amiram Eldar_, Jun 30 2023 *)
%o A103638 (PARI) a(n) = sumdiv(n, d, (d%3==2)*d^2); \\ _Seiichi Manyama_, Jun 30 2023
%K A103638 nonn
%O A103638 1,2
%A A103638 _Ralf Stephan_, Feb 11 2005