A213204 Number of terms of the Collatz (3x+1) trajectory of n that are greater than or equal to n.

1, 1, 6, 1, 3, 4, 13, 1, 14, 2, 9, 2, 4, 9, 12, 1, 5, 8, 11, 1, 3, 5, 8, 1, 11, 2, 103, 4, 6, 9, 98, 1, 11, 3, 6, 3, 5, 6, 18, 1, 98, 2, 11, 2, 4, 6, 93, 1, 6, 5, 8, 1, 3, 96, 99, 1, 10, 2, 12, 5, 7, 92, 94, 1, 6, 4, 7, 1, 3, 4, 88, 1, 98, 2, 8, 2, 4, 11, 14

Offset: 1

Author

Jayanta Basu, Mar 01 2013

Keywords

• nonn

Examples

			For n=3, the Collatz trajectory is 3, 10, 5, 16, 8, 4, 2, 1 and hence a(3)=6.
		

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A076228, A222597.

Programs

Mathematica

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; Table[Length[Select[Collatz[n], # >= n &]], {n, 100}]

Formula

a(n) = A222597(n) - 1.