%I #9 Jul 10 2015 19:59:18
%S 1,7,11,19,31,43,163,283,403,1111,1123,1243,1303,1549,1963,4123,9643,
%T 10003,11539,21431,76963,97031,468109,1351963,4553323,4778471,5163139,
%U 6563551,7618843,45214123,65704243,161738803,202903723
%N Analog of A006684 for the 7x+1 problem (cf. A133421).
%C The 7x+1 map sends x to x/2 if x is even, x/3 if x is divisible by 3, x/5 if x is divisible by 5, otherwise 7x+1.
%H N. J. A. Sloane, <a href="/A133425/b133425.txt">Table of n, a(n) for n=1..53</a> (from the web page of Tomás Oliveira e Silva)
%H Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/3x+1.html">The px+1 problem</a>
%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%Y Cf. A133421, A133426, A133419, ...
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Nov 27 2007