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 A104020 #12 Feb 13 2021 01:11:52
%S A104020 4,9,16,18,25,32,36,48,49,50,64,72,75,81,98,100,108,121,128,144,147,
%T A104020 162,169,180,192,196,200,225,242,243,245,256,288,289,294,300,320,324,
%U A104020 338,361,363,384,392,400,405,432,441,448,450,484,486,500,507,512,529,567
%N A104020 Numbers that can be represented as k^2*j, 0 < j <= k.
%t A104020 Take[ Union[ Flatten[ Table[ k^2*j, {k, 25}, {j, k - 1}]]], 56]
%Y A104020 Cf. A104021, A102354, A104022, A104024, A104026.
%K A104020 nonn
%O A104020 1,1
%A A104020 _Leroy Quet_ and _Robert G. Wilson v_, Feb 24 2005