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 A167208 #7 Apr 12 2023 10:52:14 %S A167208 12,123,234,345,456,567,678,789,890,901,1012,1123,1234,1345,1456,1567, %T A167208 1678,1789,1890,1901,2012,2123,2234,2345,2456,2567,2678,2789,2890, %U A167208 2901,3012,3123,3234,3345,3456,3567,3678,3789,3890,3901,4012,4123 %N A167208 Append two digits, each increasing by one modulo 10 from the last digit of the positive integers. 0 -> 12 1 -> 123 2 -> 234 .. 9 -> 901 10 -> 1012. %K A167208 base,easy,nonn %O A167208 0,1 %A A167208 _Felix Tubiana_, Oct 30 2009