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

Offset: 2

Author

Chai Wah Wu, Jul 27 2017

Keywords

• nonn
• base

Comments

Base 3 analog of A195264 and A230627.

Links

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

Crossrefs

Cf. A290328, A230627, A289667.

Programs

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 *)