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 A033099 #8 Nov 14 2012 18:07:54
%S A033099 0,0,1,0,0,0,1,1,1,1,2,2,3,2,5,2,3,4,5,2,5,3,6,4,4,3,8,5,5,6,8,3,8,4,
%T A033099 7,5,5,6,10,5,6,7,11,6,10,6,9,9,7,6,13,7,9,9,11,7,12,10,13,9,9,8,17,6,
%U A033099 8,11,12,9,12,8,11,9,13,8,18,10,10,13,13,10
%N A033099 Number of 3's when n is written in base b for 2<=b<=n+1.
%t A033099 f[n_] := Count[Flatten@ Table[ IntegerDigits[n, b], {b, 2, n + 1}], 3]; Array[f, 80] (* _Robert G. Wilson v_, Nov 14 2012 *)
%Y A033099 Cf. A033093, A033095, A033097, A033100, A033101, A033103, A033105, A033107, A033109, A033111.
%K A033099 nonn,base
%O A033099 1,11
%A A033099 _Clark Kimberling_