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A354170 Odd numbers whose Collatz trajectory includes 11 odd numbers.

%I A354170 #17 Jun 02 2022 22:02:05
%S A354170 57,59,115,119,229,237,461,465,473,477,507,513,917,931,943,945,947,
%T A354170 949,971,987,1015,1025,1027,1031,1129,1131,1845,1857,1861,1867,1881,
%U A354170 1887,1891,1893,1905,1909,1943,1945,1953,1975,2029,2051,2053,2055,2059,2063,2073
%N A354170 Odd numbers whose Collatz trajectory includes 11 odd numbers.
%H A354170 Wikipedia, <a href="https://en.wikipedia.org/wiki/Collatz_conjecture">Collatz Conjecture</a>
%H A354170 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%F A354170 { A005408 } intersect { A072466 }. - _Alois P. Heinz_, May 18 2022
%e A354170 119 is a term since its Collatz trajectory is 119, 358, 179, 538, 269, 808, 404, 202, 101, 304, 152, 76, 38, 19, 58, 29, 88, 44, 22, 11, 34, 17, 52, 26, 13, 40, 29, 10, 5, 16, 8, 4, 2, 1, which has 11 odd numbers.
%p A354170 b:= proc(n) option remember; irem(n, 2, 'r')+
%p A354170       `if`(n=1, 0, b(`if`(n::odd, 3*n+1, r)))
%p A354170     end:
%p A354170 q:= n-> is(n::odd and b(n)=11):
%p A354170 select(q, [$1..5000])[];  # _Alois P. Heinz_, May 18 2022
%t A354170 q[n_] := Count[NestWhileList[If[OddQ[#], 3 # + 1, #/2] &, n, # > 1 &], _?OddQ] == 11; Select[2*Range[1000] - 1, q] (* _Amiram Eldar_, May 18 2022 *)
%Y A354170 Cf. A005408, A072466, A072197.
%K A354170 nonn
%O A354170 1,1
%A A354170 _Krishna Kumar Arumugam_, May 18 2022