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 A103756 #10 Jun 10 2023 13:47:28
%S A103756 1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,
%T A103756 1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,2,2,5,2,2,2,2,2,2,1,1,
%U A103756 1,2,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1
%N A103756 Number of contiguous digits i in the counting numbers, for i=2.
%C A103756 Write the natural numbers as an infinite sequence of digits, starting at the left; and count the digits of each group of "2"'s you encounter (the smallest "groups" have one "2").
%H A103756 Harvey P. Dale, <a href="/A103756/b103756.txt">Table of n, a(n) for n = 1..1000</a>
%e A103756 a(1)=1: the first "2" of the counting numbers, isolated.
%e A103756 a(2)=1: the second "2", second digit of number 12, isolated.
%e A103756 a(3)=1 the first digit of number 20, isolated.
%e A103756 a(4)=1: the first digit of number 21, isolated.
%e A103756 a(5)=3: two "2"'s of 22 followed by one "2" of 23 = three "2"'s, the next group of "2"'s.
%t A103756 Length/@Select[Split[Flatten[IntegerDigits/@Range[300]]],Union[#]=={2}&] (* _Harvey P. Dale_, Jun 10 2023 *)
%K A103756 nonn,base
%O A103756 1,5
%A A103756 _Alexandre Wajnberg_, Mar 28 2005