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 A041012 #7 Aug 13 2022 12:57:18 %S A041012 1,2,34, %T A041012 35363738394041424344454647484950515253545556575859606162636465666768 %N A041012 Concatenate the next a(n) integers to get the n+1 term. %F A041012 a(n+1) = (a(n)+1).(a(n)+2). ... .(a(n)+a(n)) %t A041012 NestList[FromDigits[Flatten[IntegerDigits/@Range[#+1,2#]]]&,1,3] (* _Harvey P. Dale_, Aug 13 2022 *) %K A041012 base,easy,nonn %O A041012 0,2 %A A041012 _Dann Toliver_