A039501 Iterations of "n->n/2 if n even, n->3n-1 if n odd" (A001281) starting at these numbers reach 5.

5, 7, 9, 10, 13, 14, 18, 19, 20, 26, 27, 28, 35, 36, 38, 40, 47, 51, 52, 54, 56, 63, 70, 72, 75, 76, 80, 81, 89, 93, 94, 102, 104, 107, 108, 112, 119, 121, 125, 126, 133, 139, 140, 143, 144, 149, 150, 152, 159, 160, 161, 162, 167, 177, 178, 181, 186, 187, 188, 191

Offset: 1

Author

Christian G. Bower, Feb 15 1999

Keywords

• nonn
• easy

Crossrefs

Cf. A037084, A039500-A039505.

Programs

Mathematica

it5Q[n_]:=Last[NestWhileList[If[EvenQ[#],#/2,3#-1]&,n,#!=5&,1,100]]==5; Select[Range[200],it5Q] (* Harvey P. Dale, May 09 2012 *)