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 A157428 #13 Feb 16 2025 08:33:09
%S A157428 54,174,550,574,588,608,678,740,740,790,798,804,874,944,986,986,994,
%T A157428 1034,1064,1104,1104,1158,1208,1274,1308,1308,1308,1308,1406,1420,
%U A157428 1462,1462,1462,1494,1494,1550,1580,1580,1610,1624,1638,1650,1664,1664,1664
%N A157428 Lower left-hand x-coordinates of invisible 2 X 2 squares with 0 < y < x.
%H A157428 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/VisiblePoint.html">Visible Point</a>
%e A157428 {54, 20}, {174, 98}, {550, 114}, {574, 368}, {588, 494}, {608, 474}, ...
%Y A157428 Cf. A157426, A157427, A157429, A325602, A325603, A325604, A325605, A325606, A325607.
%K A157428 nonn
%O A157428 1,1
%A A157428 _Eric W. Weisstein_, Mar 01 2009