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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
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
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
KEYWORD
nonn,more,base
AUTHOR
Chai Wah Wu, Jul 27 2017
STATUS
approved