cp's OEIS Frontend

A080029 a(n) is taken to be the smallest positive integer not already present which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 3".

%I A080029 #14 Jun 27 2021 18:45:16
%S A080029 0,2,3,6,5,9,12,8,15,18,11,21,24,14,27,30,17,33,36,20,39,42,23,45,48,
%T A080029 26,51,54,29,57,60,32,63,66,35,69,72,38,75,78,41,81,84,44,87,90,47,93,
%U A080029 96,50,99,102,53,105,108,56,111,114,59,117,120,62,123,126,65,129,132,68
%N A080029 a(n) is taken to be the smallest positive integer not already present which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 3".
%H A080029 Michael S. Branicky, <a href="/A080029/b080029.txt">Table of n, a(n) for n = 0..9999</a>
%H A080029 B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">Numerical analogues of Aronson's sequence</a>, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
%H A080029 B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="https://arxiv.org/abs/math/0305308">Numerical analogues of Aronson's sequence</a>, arXiv:math/0305308 [math.NT], 2003.
%F A080029 a(3m)=6m, a(3m+1)=3m+2, a(3m+2)=6m+3.
%t A080029 {#+1,2#-1,2#}[[Mod[ #,3,1]]]&/@Range[0,80]  (* _Federico Provvedi_, Jun 15 2021 *)
%o A080029 (Python)
%o A080029 def a(n): m, r = divmod(n, 3); return 3*(2-r%2)*m + (r > 0)*(r+1)
%o A080029 print([a(n) for n in range(68)]) # _Michael S. Branicky_, Jun 15 2021
%Y A080029 Cf. A079000, A079313, A080030, A080031.
%K A080029 easy,nonn
%O A080029 0,2
%A A080029 _N. J. A. Sloane_, Mar 14 2003
%E A080029 More terms from _Matthew Vandermast_, Mar 20 2003