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 A037977 #9 Apr 09 2023 08:56:22 %S A037977 5,10,15,16,20,22,23,26,31,32,37,40,41,43,47,48,53,58,60,61,62,65,66, %T A037977 67,69,74,79,80,81,82,83,88,89,90,91,92,93,94,95,96,101,104,105,107, %U A037977 111,112,117,122,124,125,126,129,130,131,133,138,143,144,148,150 %N A037977 Numbers whose maximal base 4 run length is 2. %t A037977 Select[Range[200],Max[Length/@Split[IntegerDigits[#,4]]]==2&] (* _Harvey P. Dale_, Apr 09 2023 *) %Y A037977 Cf. A043278. %K A037977 nonn,base %O A037977 1,1 %A A037977 _Clark Kimberling_ %E A037977 More terms from _Harvey P. Dale_, Apr 09 2023