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 A033832 #17 Sep 23 2019 10:43:29
%S A033832 1,40,100,208,928,1044,3904,10692,17444,29524,36652,45980,87604,91044,
%T A033832 136808,158652,161564,171028,187068,218652,230044,260608,287868,
%U A033832 406812,438124,450492,583110,665684,719550,731850,736648,865444,1045504
%N A033832 Sum of odd divisors of n < sqrt(n) = sum of even divisors of n < sqrt(n).
%C A033832 All terms except first one appear to be even. - _Michel Marcus_, Jul 15 2013
%H A033832 Amiram Eldar, <a href="/A033832/b033832.txt">Table of n, a(n) for n = 1..500</a>
%H A033832 <a href="http://www.geocities.co.jp/Technopolis/1793/kaleido-e.htm">kaleidoscopic numbers</a> [broken link]
%t A033832 aQ[n_] := DivisorSum[n, # * (-1)^# &, # < Sqrt[n] & ] == 0; Select[Range[10^4], aQ] (* _Amiram Eldar_, Sep 23 2019 *)
%o A033832 (PARI) isok(n) = {so = 0; se = 0; fordiv (n, d, if (d < sqrt(n), if (d % 2, so += d, se += d))); return (so == se);} \\ _Michel Marcus_, Jul 14 2013
%Y A033832 Cf. A070039, A113184.
%K A033832 easy,nonn
%O A033832 1,2
%A A033832 _Naohiro Nomoto_
%E A033832 Prepended a(1)=1, _Michel Marcus_, Jul 15 2013