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%I #19 Oct 15 2018 16:29:45
%S 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 32,34,37,38,40,41,43,44,46,47,48,49,50,52,53,56,58,59,61,62,64,65,67,
%U 68,71,73,74,76,79,80,82,83,86,88,89,92,94,97,98,100,101
%N Numbers such that all divisors occur in their Collatz trajectories.
%H Reinhard Zumkeller, <a href="/A207674/b207674.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CollatzProblem.html">Collatz Problem</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Collatz_conjecture">Collatz conjecture</a>
%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%t coll[n_]:=NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#>1&]; Select[Range[101],Complement[Divisors[#],coll[#]]=={}&] (* _Jayanta Basu_, May 27 2013 *)
%o (Haskell)
%o import Data.List (intersect)
%o a207674 n = a207674_list !! (n-1)
%o a207674_list = filter
%o (\x -> a027750_row x `intersect` a070165_row x == a027750_row x) [1..]
%Y Cf. A027750, A070165, A006370, A207675 (complement), A000079 and A000040 are subsequences.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Feb 20 2012
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