A290329 - OEIS

A290329

Iterate the map x -> A289667(x) starting at n; sequence gives primes reached, or -1 if no prime is ever reached.

2, 3, 71, 5, 71, 7, 71, 11, 23, 11, 5261, 13, 17, 23, 703455573449, 17, 703455573449, 19, 5261, 71, 703455573449, 23, 727, 17, 67, 21544131687786037881228990839860266551231, 79, 29, 21544131687786037881228990839860266551231, 31, 23, 239, 71, 229, 227, 37, 73

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OFFSET

2,1

COMMENTS

Base 3 analog of A195264 and A230627.

LINKS

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

MAPLE

A290329 := proc(n)

local nitr ;

nitr := n ;

while ( not isprime(nitr) and nitr <> 1) do

nitr := A289667(nitr) ;

end do:

return nitr ;

end proc:

seq(A290329(n), n=1..20) ; # R. J. Mathar, Aug 05 2017

MATHEMATICA

Table[NestWhile[FromDigits[#, 3] &@ Flatten@ Map[IntegerDigits[#, 3] &, FactorInteger[#] /. {p_, e_} /; p > 0 :> If[e == 1, p, {p, e}]] &, n, ! PrimeQ@ # &], {n, 2, 38}] (* Michael De Vlieger, Jul 29 2017 *)

CROSSREFS

Cf. A290328, A230627, A289667.

Sequence in context: A257173 A232618 A115892 * A145531 A140546 A234237

Adjacent sequences: A290326 A290327 A290328 * A290330 A290331 A290332

KEYWORD

nonn,base

AUTHOR

Chai Wah Wu, Jul 27 2017

STATUS

approved