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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. +0
3
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; listen)
OFFSET

0,8

COMMENT

See A102421 for further comments.

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: A004458 A082123 A050256 this_sequence A010856 A060360 A081702

Adjacent sequences: A102420 A102421 A102422 this_sequence A102424 A102425 A102426

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

More terms from Robert G. Wilson v Sep 20 2006

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Last modified December 17 13:29 EST 2009. Contains 170826 sequences.


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