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.

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

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