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A290328 Iterate the map x -> A289667(x) starting at n; sequence gives number of steps to reach a prime, or -1 if no prime is ever reached. 2
0, 0, 4, 0, 3, 0, 3, 1, 1, 0, 7, 0, 2, 2, 20, 0, 19, 0, 5, 2, 19, 0, 4, 1, 1, 52, 1, 0, 51, 0, 1, 2, 1, 2, 1, 0, 1, 4, 51, 0, 2, 0, 1, 20, 5, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

COMMENTS

Base 3 analog of A230626. See A290350 for the trajectory of 48.

If a(48) != -1, then a(48) > 120. - Chai Wah Wu, Jul 29 2017

LINKS

Table of n, a(n) for n=2..47.

MATHEMATICA

Table[-1 + Length@ NestWhileList[FromDigits[#, 3] &@ Flatten@ Map[IntegerDigits[#, 3] &, FactorInteger[#] /. {p_, e_} /; p > 0 :> If[e == 1, p, {p, e}]] &, n, ! PrimeQ@ # &], {n, 2, 47}] (* Michael De Vlieger, Jul 29 2017 *)

CROSSREFS

Cf. A289667, A230626, A195264, A290350, A290329.

Sequence in context: A057075 A281653 A327305 * A200682 A263618 A156788

Adjacent sequences:  A290325 A290326 A290327 * A290329 A290330 A290331

KEYWORD

nonn,more,base

AUTHOR

Chai Wah Wu, Jul 27 2017

STATUS

approved

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Last modified September 18 09:05 EDT 2021. Contains 347518 sequences. (Running on oeis4.)