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 A325440 #5 May 02 2019 16:03:57
%S A325440 1,3,4,6,9,10,12,13,14,15,16,18,20,21,22,24,28,30,32,33,34,36,37,40,
%T A325440 42,45,46,48,49,50,51,52,54,56,57,58,60,61,64,66,68,69,70,72,74,75,76,
%U A325440 77,78,80,81,82,84,85,86,87,88,90,92,93,94,96,100,102,104
%N A325440 a(n) is the least number not 2*a(m)-1 or 3*a(m)-1 for any m < n.
%H A325440 Clark Kimberling, <a href="/A325440/b325440.txt">Table of n, a(n) for n = 1..10000</a>
%e A325440 The sequence necessarily starts with 1. The next 2 terms are determined as follows: because a(1) = 1, the number 2 is disallowed, so that a(2) = 3, whence the numbers 5 and 8 are disallowed, and a(3) = 4. See A325417 for a guide to related sequences.
%t A325440 a = {1}; Do[AppendTo[a, NestWhile[# + 1 &, Last[a] + 1, Apply[Or,
%t A325440 Map[MemberQ[a, #] &, Select[Flatten[{(#+1)/2, (#+1)/3}],
%t A325440 IntegerQ]]] &]], {150}]; a (* A325440 *)
%t A325440 Complement[Range[Last[a]], a] (* A325441 *)
%t A325440 (* _Peter J. C. Moses_, Apr 25 2019 *)
%Y A325440 Cf. A325417, A325441.
%K A325440 nonn,easy
%O A325440 1,2
%A A325440 _Clark Kimberling_, May 02 2019