

A084923


Consider the sequence b(1) = n, b(k) is the greatest prime factor of 3*b(k1)+2. It is conjectured that this always becomes cyclic; a(n) = length of cycle (or 0 if no cycle is reached).


1



20, 1, 22, 21, 19, 20, 20, 20, 27, 2, 21, 25, 19, 22, 21, 20, 19, 21, 24, 26, 20, 20, 19, 28, 22, 20, 20, 20, 26, 20, 25, 21, 30, 20, 26, 22, 27, 27, 20, 29, 19, 2, 19, 28, 25, 21, 20, 21, 22, 25, 26, 20, 19, 20, 6, 20, 31, 22, 23, 20, 28, 21, 21, 23, 27, 20, 27, 22, 25, 20, 19, 22
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..72.


MATHEMATICA

f[n_] := Flatten[ Table[ # [[1]], {1} ] & /@ FactorInteger[ 3n + 2 ]][[ 1]]; Table[ Length[ NestWhileList[f, n, UnsameQ, All]]  1, {n, 1, 72}]


CROSSREFS

Cf. A083557.
Sequence in context: A003833 A040418 A140116 * A141589 A162153 A040419
Adjacent sequences: A084920 A084921 A084922 * A084924 A084925 A084926


KEYWORD

nonn


AUTHOR

Robert G. Wilson v & Jud McCranie, Jun 11 2003


STATUS

approved



