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 A202340 #23 Mar 09 2025 13:05:52 %S A202340 1,2,1,1,2,2,1,2,1,1,2,1,1,2,2,1,1,2,2,1,2,1,1,2,2,1,2,1,1,2,1,1,2,2, %T A202340 1,2,1,1,2,1,1,2,2,1,1,2,2,1,2,1,1,2,1,1,2,2,1,1,2,2,1,2,1,1,2,2,1,2, %U A202340 1,1,2,1,1,2,2,1,1,2,2,1,2,1,1,2,2,1 %N A202340 Number of times n occurs in Hofstadter H-sequence A005374. %C A202340 a(A202341(n)) = 1; a(A202342(n)) = 2. %H A202340 Reinhard Zumkeller, <a href="/A202340/b202340.txt">Table of n, a(n) for n = 0..10000</a> %H A202340 Jeffrey Shallit, <a href="https://arxiv.org/abs/2503.01026">The Narayana Morphism and Related Words</a>, arXiv:2503.01026 [math.CO], 2025. %H A202340 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HofstadterH-Sequence.html">Hofstadter H-Sequence</a>. %H A202340 Wikipedia, <a href="http://en.wikipedia.org/wiki/Hofstadter_sequence">Hofstadter sequence</a>. %H A202340 <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>. %F A202340 a(n) = A136495(n+1) - A136495(n) for n > 0. - _Alan Michael Gómez Calderón_, Dec 23 2024 %o A202340 (Haskell) %o A202340 import Data.List (group) %o A202340 a202340 n = a202340_list !! n %o A202340 a202340_list = map length $ group a005374_list %Y A202340 Cf. A005374, A136495, A202341, A202342. %K A202340 nonn %O A202340 0,2 %A A202340 _Reinhard Zumkeller_, Dec 17 2011