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 A043503 #16 Apr 24 2021 21:29:50 %S A043503 333,1333,2333,3033,3133,3233,3303,3313,3323,3330,3331,3332,3334,3335, %T A043503 3336,3337,3338,3339,3343,3353,3363,3373,3383,3393,3433,3533,3633, %U A043503 3733,3833,3933,4333,5333,6333,7333,8333,9333,10333 %N A043503 Numbers having three 3's in base 10. %H A043503 Daniel Starodubtsev, <a href="/A043503/b043503.txt">Table of n, a(n) for n = 1..10000</a> %t A043503 Select[Range[11000],DigitCount[#,10,3]==3&] (* _Harvey P. Dale_, Apr 13 2015 *) %Y A043503 Subsequence of A011533. %K A043503 nonn,base %O A043503 1,1 %A A043503 _Clark Kimberling_