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 A030597 #11 Dec 30 2018 00:01:36
%S A030597 1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%T A030597 1,1,1,1,1,1,1,1,1,1,1,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%U A030597 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,2,2,2
%N A030597 Length of n-th run of digit 2 in A030588.
%H A030597 Antti Karttunen, <a href="/A030597/b030597.txt">Table of n, a(n) for n = 1..20000</a>
%o A030597 (PARI)
%o A030597 up_to = 20000;
%o A030597 A030597list(up_to,d=2) = { my(v=vector(up_to),ds=List([]),o=1,j=1,rl=0,i=0); while(i<up_to,if(j>#ds,ds=digits(o,6);j=1;o+=2); if(d==ds[j],rl++,if(rl,i++; v[i] = rl; rl=0)); j++); (v); };
%o A030597 v030597 = A030597list(up_to);
%o A030597 A030597(n) = v030597[n]; \\ _Antti Karttunen_, Dec 24 2018
%Y A030597 Cf. A030588, A030596, A030598, A030599, A030600.
%K A030597 nonn,base
%O A030597 1,13
%A A030597 _Clark Kimberling_
%E A030597 Terms corrected (first incorrect term was at a(61)) and more terms added by _Antti Karttunen_, Dec 24 2018