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 A080903 #17 Jul 29 2025 15:57:09
%S A080903 1,3,7,9,11,13,17,19,23,25,29,31,35,37,39,41,45,47,51,53,55,57,61,63,
%T A080903 67,69,71,73,77,79,83,85,87,89,93,95,99,101,105,107,111,113,115,117,
%U A080903 121,123,127,129,131,133,137,139,143,145,149,151,155,157,159
%N A080903 a(1)=1; for n>1, a(n)=a(n-1)+4 if n is already in the sequence, a(n)=a(n-1)+2 otherwise.
%C A080903 In the Fokkink-Joshi paper, this sequence is the Cloitre (0,1,4,2)-hiccup sequence. - _Michael De Vlieger_, Jul 29 2025
%H A080903 Ivan Neretin, <a href="/A080903/b080903.txt">Table of n, a(n) for n = 1..1000</a>
%H A080903 Benoit Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL6/Cloitre/cloitre2.html">Numerical analogues of Aronson's sequence</a>, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
%H A080903 Benoit Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://arXiv.org/abs/math.NT/0305308">Numerical analogues of Aronson's sequence</a>, arXiv:math/0305308 [math.NT], 2003.
%H A080903 Robbert Fokkink and Gandhar Joshi, <a href="https://arxiv.org/abs/2507.16956">On Cloitre's hiccup sequences</a>, arXiv:2507.16956 [math.CO], 2025. See pp. 2-3.
%t A080903 Fold[Append[#1, #1[[-1]] + If[MemberQ[#1, #2], 4, 2]] &, {1}, Range[2, 59]] (* _Ivan Neretin_, Mar 03 2016 *)
%Y A080903 Cf. A080578, A080900, A086398.
%K A080903 nonn
%O A080903 1,2
%A A080903 _Benoit Cloitre_, Apr 01 2003