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 A104647 #8 May 12 2025 13:42:38
%S A104647 0,1,1,2,3,5,8,6,6,12,8,9,17,13,16,14,14,28,24,14,18,32,28,14,18,32,
%T A104647 24,29,25,25,50,44,30,41,37,8,9,17,26,43,29,31,60,48,20,23,43,66,61,
%U A104647 29,40,69,57,20,23,43,66,52,60,53,53,106,97,77,46,58,104,95,63,89,82,29,39,68
%N A104647 a(n) = a(n-1) mod n + a(n-2) mod n; a(0) = 0, a(1) = 1.
%C A104647 a(n) <= a(n-1) + a(n-2) < 2*n for n>0, see A105859 for numbers i such that a(i)=a(i-1)+a(i-2) and A105860 for numbers j with a(j)<a(j-1)+a(j-2); - _Reinhard Zumkeller_, Apr 23 2005
%C A104647 A105855 = (first differences) and A105856 = (partial sums); records occur at A105857: A105858(n) = a(A105857(n)). - _Reinhard Zumkeller_, Apr 23 2005
%H A104647 Ivan Neretin, <a href="/A104647/b104647.txt">Table of n, a(n) for n = 0..10000</a>
%t A104647 Fold[Append[#1, Mod[#1[[-1]], #2] + Mod[#1[[-2]], #2]] &, {0, 1}, Range[2, 73]] (* _Ivan Neretin_, Jun 18 2018 *)
%t A104647 nxt[{n_,a_,b_}]:={n+1,b,Mod[a,n+1]+Mod[b,n+1]}; NestList[nxt,{1,0,1},80][[;;,2]] (* _Harvey P. Dale_, May 12 2025 *)
%Y A104647 Cf. A079777
%K A104647 nonn
%O A104647 0,4
%A A104647 _Reinhard Zumkeller_, Apr 21 2005