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 A043499 #17 Aug 23 2021 13:46:33 %S A043499 222,1222,2022,2122,2202,2212,2220,2221,2223,2224,2225,2226,2227,2228, %T A043499 2229,2232,2242,2252,2262,2272,2282,2292,2322,2422,2522,2622,2722, %U A043499 2822,2922,3222,4222,5222,6222,7222,8222,9222,10222,11222,12022,12122,12202,12212 %N A043499 Numbers having three 2's in base 10. %H A043499 Daniel Starodubtsev, <a href="/A043499/b043499.txt">Table of n, a(n) for n = 1..10000</a> %t A043499 Select[Range[13000],DigitCount[#,10,2]==3&] (* _Harvey P. Dale_, Aug 23 2021 *) %Y A043499 Subsequence of A011532. %K A043499 nonn,base %O A043499 1,1 %A A043499 _Clark Kimberling_