A008899 x -> x/2 if x even, x -> 3x - 1 if x odd.

87, 260, 130, 65, 194, 97, 290, 145, 434, 217, 650, 325, 974, 487, 1460, 730, 365, 1094, 547, 1640, 820, 410, 205, 614, 307, 920, 460, 230, 115, 344, 172, 86, 43, 128, 64, 32, 16, 8, 4, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1

Offset

0,1

References

R. K. Guy, Unsolved Problems in Number Theory, E16.

Links

Table of n, a(n) for n=0..48.

Index entries for linear recurrences with constant coefficients, signature (0, 1).

Example

87 is odd, so it's followed by 3 * 87 - 1 = 260.
260 is even, so it's followed by 260/2 = 130.

Mathematica

NestList[If[EvenQ[#], #/2, 3# - 1] &, 87, 100] (* Alonso del Arte, Aug 22 2017 *)

Crossrefs

Cf. A008879.

Sequence in context: A133524 A304509 A020314 * A008879 A186063 A186055

Adjacent sequences: A008896 A008897 A008898 * A008900 A008901 A008902

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved