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 A141033 #10 Jan 23 2022 13:52:53 %S A141033 0,1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,100,101,121,131,141, %T A141033 151,161,171,181,191,200,202,212,232,242,252,262,272,282,292,300,303, %U A141033 313,323,343,353,363,373,383,393,400,404 %N A141033 Numbers that cannot be formed by the concatenation of previous terms. %C A141033 Previous terms can appear in any order but can be used at most once. - _Paolo P. Lava_, Mar 04 2010 %e A141033 465 is not in the sequence because 4 U 6 U 5 -> 465; %e A141033 466 is not in the sequence because 4 U 66 -> 466; %e A141033 1313 is not in the sequence because 1 U 313 or 131 U 3 -> 1313. %Y A141033 Cf. A141409. %K A141033 nonn,base %O A141033 1,3 %A A141033 _Paolo P. Lava_ and _Giorgio Balzarotti_, Jul 30 2008, Aug 04 2008 %E A141033 Corrected by _Paolo P. Lava_, Mar 03 2010