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 A085855 #12 Sep 04 2025 20:56:42
%S A085855 0,1,1,0,0,0,0,1,1,0,0,0,1,0,0,1,0,1,0,2,0,1,3,0,0,0,2,2,3,1,0,1,1,0,
%T A085855 0,0,1,2,1,0,2,3,1,0,1,3,3,2,0,0,1,2,1,3,1,1,2,1,1,1,1,2,1,1,2,3,0,1,
%U A085855 2,2,2,4,2,1,1,3,1,0,1,2,1,1,5,1,2,3,2,2,5,4,3,1,2,5,3,1,1,2,2,2,3,5,2,1,0
%N A085855 Number of 1's in decimal expansion of Fibonacci(n).
%H A085855 Alois P. Heinz, <a href="/A085855/b085855.txt">Table of n, a(n) for n = 0..20000</a>
%e A085855 Fibonacci(10)=55, so a(10)=0 and Fibonacci(21)=10946, so a(21)=1.
%t A085855 Table[DigitCount[Fibonacci[n]][[1]], {n, 0, 200}] (* _Vladimir Joseph Stephan Orlovsky_, Jul 01 2011 *)
%Y A085855 Cf. 0's A085854, 2's A085856, 3's A085857, 4's A085858, 5's A085859, 6's A085860, 7's A085861, 8's A085862, 9's A085863.
%K A085855 base,nonn,changed
%O A085855 0,20
%A A085855 _Jason Earls_, Jul 06 2003