OFFSET
1,2
MATHEMATICA
colln[n_]:= NestWhile[If[EvenQ[#], #/2, 3#-1] &, n, FreeQ[{1, 5, 17}, #] &]; Select[Range[1, 289, 2], colln[#] == 1 &] (* Jayanta Basu, Jun 06 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Christian G. Bower, Feb 15 1999
STATUS
approved