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A102423 Start at 2n+1, iterate the map x -> A102421(x); sequence gives smallest number in resulting cycle, or -1 if the trajectory never cycles. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

COMMENTS

See A102421 for further comments.

LINKS

Table of n, a(n) for n=0..94.

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, MemberQ[{1, 17, 19, 43, 97, 109}, # ] &]; Table[ If[ f[2n + 1] == 1, 1, 17], {n, 0, 94}] (* Robert G. Wilson v, Sep 20 2006 *)

CROSSREFS

Sequence in context: A172091 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

STATUS

approved

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Last modified October 17 10:50 EDT 2017. Contains 293469 sequences.