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 A255724 #22 Aug 23 2021 06:36:07
%S A255724 1,2,3,4,5,6,7,8,9,10,11,13,14,15,16,17,18,20,22,24,25,26,27,29,30,33,
%T A255724 35,36,37,38,40,44,46,47,49,50,55,57,58,60,66,69,70,77,80,88,90,99,
%U A255724 100,102,103,104,105,106,107,108,109,112,114,115,116,117,118,122
%N A255724 List of numbers such that no number, nor its reverse, is in the concatenation of all previous terms.
%e A255724 After listing 1..11, 12 is not listed as "12" is found in the concatenated earlier terms. After continuing with 13..18, 19 is not listed as "91" is likewise found.
%o A255724 (Perl) $s="";$_=0;do{$_++;if(index($s,$_)<0 && index($s,reverse)<0){print("$_ ");$s.=$_}}while(1);
%o A255724 (PARI) lista(nn) = my(d, v=[]); for(n=1, nn, for(i=0, #v-#d=digits(n), (v[i+1..i+#d]==d || v[i+1..i+#d]==Vecrev(d)) && next(2)); print1(n, ", "); v=concat(v, d)) \\ _Jinyuan Wang_, Aug 23 2021
%Y A255724 Cf. A048991.
%K A255724 nonn,base,easy
%O A255724 1,2
%A A255724 _Phil Carmody_, Mar 19 2015
%E A255724 More terms from _Jinyuan Wang_, Aug 23 2021