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 A043536 #14 Dec 26 2017 13:41:27
%S A043536 1,1,1,1,1,1,1,1,2,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,
%T A043536 2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,
%U A043536 2,1,2,2,2,2,2,2,2,2,2,1,2,2,3,3,3,3,3,3,3,2,1,2,2,2,2,2,2,2,3,2,2,3,3,3,3
%N A043536 Number of distinct base-9 digits of n.
%H A043536 Antti Karttunen, <a href="/A043536/b043536.txt">Table of n, a(n) for n = 1..66430</a>
%e A043536 As 731 = 1*(9^3) + 0*(9^2) + 0*(9^1) + 2*(9^0), it is written in base 9 (A007095) as "1002". There are three kinds of digits present, thus a(731) = 3. - _Antti Karttunen_, Dec 22 2017
%t A043536 Table[Count[DigitCount[n,9],+_?(#>0&)],{n,100}] (* _Harvey P. Dale_, Apr 30 2015 *)
%o A043536 (PARI) A043536(n) = length(vecsort(digits(n,9),,8)); \\ _Antti Karttunen_, Dec 22 2017
%Y A043536 Cf. A007095, A043283, A044931, A044940, A044949.
%K A043536 nonn,base
%O A043536 1,9
%A A043536 _Clark Kimberling_
%E A043536 More terms from _Antti Karttunen_, Dec 22 2017