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 A207674 #20 Feb 16 2025 08:33:16
%S A207674 1,2,3,4,5,6,7,8,10,11,12,13,14,16,17,19,20,22,23,24,25,26,28,29,31,
%T A207674 32,34,37,38,40,41,43,44,46,47,48,49,50,52,53,56,58,59,61,62,64,65,67,
%U A207674 68,71,73,74,76,79,80,82,83,86,88,89,92,94,97,98,100,101
%N A207674 Numbers such that all divisors occur in their Collatz trajectories.
%H A207674 Reinhard Zumkeller, <a href="/A207674/b207674.txt">Table of n, a(n) for n = 1..10000</a>
%H A207674 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CollatzProblem.html">Collatz Problem</a>
%H A207674 Wikipedia, <a href="http://en.wikipedia.org/wiki/Collatz_conjecture">Collatz conjecture</a>
%H A207674 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%t A207674 coll[n_]:=NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#>1&]; Select[Range[101],Complement[Divisors[#],coll[#]]=={}&] (* _Jayanta Basu_, May 27 2013 *)
%o A207674 (Haskell)
%o A207674 import Data.List (intersect)
%o A207674 a207674 n = a207674_list !! (n-1)
%o A207674 a207674_list = filter
%o A207674 (\x -> a027750_row x `intersect` a070165_row x == a027750_row x) [1..]
%Y A207674 Cf. A027750, A070165, A006370, A207675 (complement), A000079 and A000040 are subsequences.
%K A207674 nonn
%O A207674 1,2
%A A207674 _Reinhard Zumkeller_, Feb 20 2012