A133420 Number of steps to reach 1 under repeated applications of the "5x+1" map of A133419, or -1 if 1 is never reached.

0, 1, 1, 2, 14, 2, 5, 3, 2, 15, 9, 3, 12, 6, 15, 4, 9, 3, 7, 16, 6, 10, 21, 4, 9, 13, 3, 7, 18, 16, 16, 5, 10, 10, 14, 4, 19, 8, 13, 17, 13, 7, 7, 11, 16, 22, 26, 5, 16, 10, 10, 14, 25, 4, 25, 8, 8, 19, 23, 17, 13, 17, 7, 6, 17, 11, 11, 11, 22, 15, 26, 5, 16, 20, 10, 9, 20, 14, 14, 18, 4, 14

Offset

1,4

Comments

The 5x+1 map sends x to x/2 if x is even, x/3 if x is divisible by 3, otherwise 5x+1.

Links

R. J. Mathar, Table of n, a(n) for n = 1..20000

R. J. Mathar, Maple program to make b-file

Tomás Oliveira e Silva, The px+1 problem

Index entries for sequences related to 3x+1 (or Collatz) problem

Crossrefs

Cf. A133419.

Sequence in context: A196815 A260120 A221234 * A227628 A298800 A138907

Adjacent sequences: A133417 A133418 A133419 * A133421 A133422 A133423

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 27 2007

Status

approved