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 A044949 #16 Dec 26 2017 13:41:39
%S A044949 1,1,1,1,1,1,1,1,2,0,2,2,2,2,2,2,2,2,2,0,2,2,2,2,2,2,2,2,2,0,2,2,2,2,
%T A044949 2,2,2,2,2,0,2,2,2,2,2,2,2,2,2,0,2,2,2,2,2,2,2,2,2,0,2,2,2,2,2,2,2,2,
%U A044949 2,0,2,2,2,2,2,2,2,2,2,0,1,3,3,3,3,3,3,3,3,1,1,1,1,1,1,1,1,1,3,3,1,3,3,3,3
%N A044949 Number of runs of odd length in the base-9 representation of n.
%H A044949 Antti Karttunen, <a href="/A044949/b044949.txt">Table of n, a(n) for n = 1..66430</a>
%F A044949 As 731 = 1*(9^3) + 0*(9^2) + 0*(9^1) + 2*(9^0), it is written in base 9 (A007095) as "1002". There is one run of even length, and two runs of length 1 (thus of odd length), thus a(731) = 2. - _Antti Karttunen_, Dec 22 2017
%t A044949 Array[Count[Map[Length, Split@ IntegerDigits[#, 9]], _?OddQ] &, 105] (* _Michael De Vlieger_, Dec 22 2017 *)
%o A044949 (PARI) A044949(n) = { my(rl=0, d, prev_d = -1, s=0); while(n>0, d = (n%9); n = ((n-d)/9); if(d==prev_d, rl++, s += (rl%2); prev_d = d; rl = 1)); (s + (rl%2)); }; \\ _Antti Karttunen_, Dec 22 2017
%Y A044949 Cf. A007095, A043283, A043536, A044940, A044931.
%K A044949 nonn,base
%O A044949 1,9
%A A044949 _Clark Kimberling_
%E A044949 More terms from _Antti Karttunen_, Dec 22 2017