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 A032612 #17 Jun 29 2025 15:05:30
%S A032612 18,29,310,411,512,613,714,815,916,1017,1118,1219,1320,1421,1522,1623,
%T A032612 1724,1825,1926,2027,2128,2229,2330,2431,2532,2633,2734,2835,2936,
%U A032612 3037,3138,3239,3340,3441,3542,3643,3744,3845,3946,4047,4148,4249
%N A032612 Concatenation of n and n+7.
%t A032612 Table[n*10^IntegerLength[n+7]+n+7,{n,50}] (* _Harvey P. Dale_, Apr 26 2025 *)
%o A032612 (Python)
%o A032612 def A032612(n): return n*(10**len(str(n+7))+1)+7 # _Chai Wah Wu_, Jun 29 2025
%Y A032612 Cf. A001704, A020338.
%K A032612 nonn,base
%O A032612 1,1
%A A032612 _Patrick De Geest_, May 15 1998