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 A325429 #7 Apr 30 2019 21:49:26
%S A325429 1,2,4,5,8,9,10,11,14,17,18,19,20,22,23,26,29,31,32,35,36,37,38,40,41,
%T A325429 44,45,47,49,50,53,56,58,59,62,63,64,65,68,71,72,74,76,77,80,81,82,83,
%U A325429 85,86,89,90,91,92,95,98,99,100,101,103,104,107,109,110
%N A325429 a(n) is the least number not 3*a(m) or floor(3*a(m)/2) for any m < n.
%H A325429 Clark Kimberling, <a href="/A325429/b325429.txt">Table of n, a(n) for n = 1..10000</a>
%e A325429 The sequence necessarily starts with 1. The next 2 terms are determined as follows: because a(1) = 1, the number 3 is disallowed, so that a(2) = 2, whence the numbers 3 and 6 are disallowed, and a(3) = 4. See A325417 for a guide to related sequences.
%t A325429 a = {1}; Do[AppendTo[a, NestWhile[# + 1 &, Last[a] + 1, Apply[Or,
%t A325429 Map[MemberQ[a, #] &, Select[Flatten[{#/3,
%t A325429 If[Mod[#, 3] == 0, (2 #)/3, 0] + If[Mod[#, 3] == 1, 1/3 (1 + 2 #), 0]}],
%t A325429 IntegerQ || # == 0]]] &]], {150}]; a (* A325429 *)
%t A325429 Complement[Range[Last[a]], a] (* A325430 *)
%t A325429 (* _Peter J. C. Moses_, Apr 25 2019 *)
%Y A325429 Cf. A325417, A325430.
%K A325429 nonn,easy
%O A325429 1,2
%A A325429 _Clark Kimberling_, Apr 30 2019