A102423 Start at x=2n+1, iterate the map x -> A337349(x); sequence gives smallest number in the resulting cycle, or -1 if the trajectory never cycles.

1, 1, 1, 1, 1, 1, 1, 17, 17, 17, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 17, 1, 1, 17, 17, 1, 1, 1, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 17, 17, 17, 1, 1, 1, 1, 1, 1, 1, 1

Offset

0,8

Comments

See A102421 and A337349 for further comments.

Links

David A. Corneth, Table of n, a(n) for n = 0..9999

Mathematica

nextx[x_Integer] := Block[{a = x}, a = 3a + 1; While[EvenQ@a, a /= 2]; a = 3a - 1; While[EvenQ@a, a /= 2]; a]; f[n_] := NestWhile[nextx, n, FreeQ[{1, 17, 19, 43, 97, 109, 61}, # ] &]; Table[ If[ f[2n + 1] == 1, 1, 17], {n, 0, 94}] (* Robert G. Wilson v, Sep 20 2006; added 61 to comparison set used for detecting cycles, William P. Orrick, Aug 24 2020; should be "!" prefixing MemberQ, changed to FreeQ, Ray Chandler, Aug 28 2020 *)

Crossrefs

Cf. A102421, A122563 (iterations to enter cycle), A337349.

Sequence in context: A371997 A291370 A291432 * A010856 A291515 A216436

Adjacent sequences: A102420 A102421 A102422 * A102424 A102425 A102426

Keyword

nonn

Author

N. J. A. Sloane, based on email from Dan Asimov (dasimov(AT)earthlink.net), Sep 15 2006

Extensions

More terms from Robert G. Wilson v, Sep 20 2006

Replaced A102421 by A337349 in NAME. - R. J. Mathar, Aug 24 2020

Status

approved