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 A032614 #18 Feb 17 2024 10:29:21
%S A032614 110,211,312,413,514,615,716,817,918,1019,1120,1221,1322,1423,1524,
%T A032614 1625,1726,1827,1928,2029,2130,2231,2332,2433,2534,2635,2736,2837,
%U A032614 2938,3039,3140,3241,3342,3443,3544,3645,3746,3847,3948,4049,4150,4251,4352,4453,4554,4655
%N A032614 Concatenation of n and n + 9 or {n,n+9}.
%H A032614 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/NonRecursions.html">Non Recursions</a>
%t A032614 a[n_]:=n*10^Floor[Log10[n+9]+1]+n+9; Array[a,46] (* _Stefano Spezia_, Sep 04 2023 *)
%Y A032614 Cf. A001704, A020338.
%K A032614 nonn,base,easy
%O A032614 1,1
%A A032614 _Patrick De Geest_, May 15 1998
%E A032614 a(42)-a(46) from _Stefano Spezia_, Sep 04 2023