A185455 Trajectory of 7 under repeated application of the map in A185452.

7, 18, 9, 23, 58, 29, 73, 183, 458, 229, 573, 1433, 3583, 8958, 4479, 11198, 5599, 13998, 6999, 17498, 8749, 21873, 54683, 136708, 68354, 34177, 85443, 213608, 106804, 53402, 26701, 66753, 166883, 417208, 208604, 104302, 52151, 130378, 65189, 162973, 407433, 1018583, 2546458, 1273229, 3183073, 7957683, 19894208, 9947104

Offset: 1

Author

N. J. A. Sloane, Feb 04 2011

Keywords

• nonn

Comments

It is conjectured that this trajectory is unbounded, but this is an open problem.

References

• J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010; see page 89.

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to 3x+1 (or Collatz) problem

Crossrefs

Cf. A185452, A185453, A185454.

Programs

Maple

f:=n->if n mod 2 = 0 then n/2 else (5*n+1)/2; fi;
T:=proc(n,M) global f; local t1,i; t1:=[n];
for i from 1 to M-1 do t1:=[op(t1),f(t1[nops(t1)])]; od: t1; end;
T(7,120);