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 A333568 #23 Jul 20 2021 12:16:26 %S A333568 0,111,222,333,444,555,666,777,888,999,1012,1103,1230,1321,1456,1547, %T A333568 1674,1765,2023,2132,2201,2310,2467,2576,2645,2754,3031,3120,3213, %U A333568 3302,3475,3564,3657,3746,4048,4159,4284,4395,4806,4917,5069,5178,5296,5387,5814 %N A333568 Lexicographically earliest sequence of nonnegative integers such that two distinct terms differ by at least 3 decimal digits. %C A333568 This is the distance 3 lexicode over the decimal alphabet. - _N. J. A. Sloane_, Jul 20 2021 %H A333568 Rémy Sigrist, <a href="/A333568/b333568.txt">Table of n, a(n) for n = 0..9999</a> %H A333568 J. H. Conway, <a href="https://doi.org/10.1016/0012-365X(90)90008-6">Integral lexicographic codes</a>, Discrete Mathematics 83.2-3 (1990): 219-235. See paragraph 3. %H A333568 J. H. Conway and N. J. A. Sloane, <a href="https://doi.org/10.1109/TIT.1986.1057187">Lexicographic codes: error-correcting codes from game theory</a>, IEEE Transactions on Information Theory, 32:337-348, 1986. %H A333568 Rémy Sigrist, <a href="/A333568/a333568.txt">C program for A333568</a> %o A333568 (C) See Links section. %Y A333568 Cf. A075926 (binary equivalent) %K A333568 nonn,base %O A333568 0,2 %A A333568 _Rémy Sigrist_, Jun 09 2020