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 A033107 #14 Aug 21 2024 05:40:21
%S A033107 0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,2,1,2,1,2,1,2,1,3,1,2,2,
%T A033107 2,1,3,1,3,2,2,1,4,1,2,2,4,1,3,1,3,3,2,1,5,2,4,3,4,2,5,3,6,3,3,2,7,2,
%U A033107 3,5,6,3,5,2,4,3,6,3,9,2,3,4,4,4,6,3,8,4,3,2
%N A033107 Number of 7's when n is written in base b for 2<=b<=n+1.
%H A033107 Robert Israel, <a href="/A033107/b033107.txt">Table of n, a(n) for n = 1..10000</a>
%p A033107 f:= proc(n) local b;`+`(seq(numboccur(7,convert(n,base,b)),b=8..n+1)) end proc:
%p A033107 map(f, [$1..100]); # _Robert Israel_, Aug 20 2024
%t A033107 f[n_] := Count[Flatten@ Table[ IntegerDigits[n, b], {b, 2, n + 1}], 7]; Array[f, 90] (* _Robert G. Wilson v_, Nov 14 2012 *)
%Y A033107 Cf. A033093, A033095, A033097, A033099, A033101, A033103, A033105, A033108, A033109, A033111.
%K A033107 nonn,base,look
%O A033107 1,23
%A A033107 _Clark Kimberling_