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 A349805 #10 Dec 11 2021 10:14:38
%S A349805 1,111,11211,1122211,112232211,11223332211,1122334332211,
%T A349805 112233444332211,11223344544332211,112233444636544332211,
%U A349805 1122334446373736544332211,11223344463737473736544332211,112233444637374666473736544332211,1122334446373746649466473736544332211,11223344463737466492319466473736544332211
%N A349805 a(n) = A261138(n)/11.
%p A349805 a:= n-> (s-> parse(cat(s, seq(s[-i], i=1..length(s))))/11)(cat("", $1..n)):
%p A349805 seq(a(n), n=1..14); # _Alois P. Heinz_, Dec 01 2021
%o A349805 (Python)
%o A349805 def A349805(n): return int((lambda x: x+x[::-1])(''.join(str(d) for d in range(1,n+1))))//11 # _Chai Wah Wu_, Dec 01 2021
%Y A349805 Cf. A261138.
%Y A349805 A109242 has the same initial terms.
%K A349805 nonn,base
%O A349805 1,2
%A A349805 _N. J. A. Sloane_, Dec 01 2021
%E A349805 More than the usual number of terms are shown in order to distinguish this from several similar sequences.