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 A157426 #13 Feb 16 2025 08:33:09
%S A157426 20,35,35,54,65,69,77,84,84,95,98,98,99,99,104,104,104,110,114,114,
%T A157426 119,119,132,132,135,135,147,153,153,159,161,170,170,170,174,174,175,
%U A157426 185,185,186,186,188,189,189,189,189,189,195,195,195
%N A157426 Lower left-hand x-coordinates of invisible 1x1 squares with 0 < y < x.
%H A157426 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/VisiblePoint.html">Visible Point</a>
%e A157426 {20, 14}, {35, 14}, {35, 20}, {54, 44}, {65, 39}, {69, 45}, {77, 21}, {84, 34}, {84, 50}, {95, 75}, ...
%Y A157426 Cf. A157426, A157428, A157429, A325602.
%Y A157426 Cf. A325603, A325604, A325605, A325606, A325607.
%K A157426 nonn
%O A157426 1,1
%A A157426 _Eric W. Weisstein_, Mar 01 2009