cp's OEIS Frontend

A202342 Numbers occurring exactly twice in Hofstadter H-sequence A005374.

%I A202342 #34 Mar 09 2025 12:51:09
%S A202342 1,4,5,7,10,13,14,17,18,20,23,24,26,29,32,33,35,38,41,42,45,46,48,51,
%T A202342 54,55,58,59,61,64,65,67,70,73,74,77,78,80,83,84,86,89,92,93,95,98,
%U A202342 101,102,105,106,108,111,112,114,117,120,121,123,126,129,130,133
%N A202342 Numbers occurring exactly twice in Hofstadter H-sequence A005374.
%C A202342 Position of the n-th occurrence of the digit 1 in A105083(n-1) for n>=1. - _Jeffrey Shallit_, Mar 08 2025
%H A202342 Reinhard Zumkeller, <a href="/A202342/b202342.txt">Table of n, a(n) for n = 1..10000</a>
%H A202342 Larry Ericksen and Peter G. Anderson, <a href="http://www.cs.rit.edu/~pga/k-zeck.pdf">Patterns in differences between rows in k-Zeckendorf arrays</a>, The Fibonacci Quarterly, Vol. 50, No. 1 (February 2012), pp. 11-18.
%H A202342 Jeffrey Shallit, <a href="https://arxiv.org/abs/2503.01026">The Narayana Morphism and Related Words</a>, arXiv:2503.01026 [math.CO], 2025.
%H A202342 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HofstadterH-Sequence.html">Hofstadter H-Sequence.</a>
%H A202342 Wikipedia, <a href="http://en.wikipedia.org/wiki/Hofstadter_sequence">Hofstadter sequence</a>
%H A202342 <a href="/index/Ho#Hofstadter">Index entries for Hofstadter-type sequences</a>
%F A202342 A202340(a(n)) = 2.
%F A202342 a(n) = A005374(A136496(n)). - _Alan Michael Gómez Calderón_, Dec 22 2024
%F A202342 a(n) = A136495(A136495(n)). - _Alan Michael Gómez Calderón_, Jan 06 2025
%o A202342 (Haskell)
%o A202342 import Data.List (elemIndices)
%o A202342 a202342 n = a202342_list !! (n-1)
%o A202342 a202342_list = elemIndices 2 a202340_list
%Y A202342 Cf. A005374, A105083, A202340, A136495, A136496, A202341 (complement).
%K A202342 nonn
%O A202342 1,2
%A A202342 _Reinhard Zumkeller_, Dec 17 2011