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Numbers n whose reverse binary representation has the following property: let a 0 mean "halving" and a 1 mean "k -> 3k+1". The number describes an operation k -> f_n(k). If the equation f_n(k) = k has a positive integer solution, n is a term in the sequence.
4

%I #4 Mar 30 2012 17:21:02

%S 4,36,140,145,200,292,1059,1136,1553,1800,2340,4150,4274,4297,4308,

%T 4389,4433,4490,4634,4696,4705,4741,4804,4876,5133,5164,5218,5254,

%U 5400,5409,5668,5712,5761,6244,6290,6312,6448,6466,6662,6800,6976

%N Numbers n whose reverse binary representation has the following property: let a 0 mean "halving" and a 1 mean "k -> 3k+1". The number describes an operation k -> f_n(k). If the equation f_n(k) = k has a positive integer solution, n is a term in the sequence.

%C Suggested by A125626.

%C Note that f_n(x) is always a linear function of x.

%H David Applegate, <a href="/A125756/b125756.txt">Table of n, a(n) for n = 1..60</a>

%Y Cf. A125626, A125755, A125754, A125757, A125710, A125711.

%K nonn

%O 1,1

%A _David Applegate_, Feb 02 2007