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 A287476 #6 Feb 16 2025 08:33:46
%S A287476 1,1,1,2,1,2,1,2,2,3,2,3,2,3,2,4,1,3,1,3,2,4,2,5,2,5,2,5,2,4,3,5,4,7,
%T A287476 2,3,3,7,1,4,1,2,3,6,2,5,1,5,2,5,2,7,2,6,2,7,2,4,5,7,5,10,2,7,2,7,2,7,
%U A287476 4,9,4,8,7,11,3,6,7,9,3,4,4,5,4,5,4,7,7,9,3,7,1,3,5,7,3,8,1,7,2,7,2
%N A287476 a(0) = a(1) = 1; a(2*n) = a(n-a(n)), a(2*n+1) = a(n-a(n)) + a(n-a(n+1)).
%C A287476 A variation on Hofstadter's Q-sequence and Stern's diatomic sequence.
%H A287476 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SternsDiatomicSeries.html">Stern's Diatomic Series</a>
%H A287476 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HofstadtersQ-Sequence.html">Hofstadter's Q-Sequence</a>
%H A287476 <a href="/index/St#Stern">Index entries for sequences related to Stern's sequences</a>
%H A287476 <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>
%t A287476 a[0] = 1; a[1] = 1; a[n_] := If[EvenQ[n], a[n/2 - a[n/2]], a[(n - 1)/2 - a[(n - 1)/2]] + a[(n - 1)/2 - a[(n + 1)/2]]]; Table[a[n], {n, 0, 100}]
%Y A287476 Cf. A002487, A005185, A287475, A287477.
%K A287476 nonn
%O A287476 0,4
%A A287476 _Ilya Gutkovskiy_, May 25 2017