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A046503 Primes with multiplicative persistence value 3. 3
47, 59, 79, 89, 97, 139, 149, 157, 179, 193, 197, 227, 229, 239, 263, 283, 293, 337, 347, 353, 359, 367, 373, 383, 389, 419, 433, 443, 449, 463, 479, 487, 491, 499, 571, 577, 593, 619, 643, 661, 673, 683, 691, 719, 733, 743, 751, 757, 797, 823, 829, 839 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Multiplicative Persistence

EXAMPLE

47 -> 4 * 7 -> [ 28 ] -> 2 * 8 -> [ 16 ] -> 1 * 6 -> [ 6 ] -> one digit in three steps.

MAPLE

filter:= proc(n) local L;

  if not isprime(n) then return false fi;

  L:= convert(convert(n, base, 10), `*`); if L < 10 then return false fi;

  L:= convert(convert(L, base, 10), `*`); if L < 10 then return false fi;

  L:= convert(convert(L, base, 10), `*`); evalb(L < 10)

end proc:

select(filter, [seq(i, i=11..1000, 2)]); # Robert Israel, Jun 05 2018

MATHEMATICA

pr3Q[n_] := Length[NestWhileList[Times @@ IntegerDigits[#] &, n, # > 9 &]] == 4; Select[Prime[Range[147]], pr3Q] (* Jayanta Basu, Jun 26 2013 *)

CROSSREFS

Cf. A046500, A046512.

Sequence in context: A104852 A061758 A309510 * A227982 A102274 A139909

Adjacent sequences:  A046500 A046501 A046502 * A046504 A046505 A046506

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Sep 15 1998

STATUS

approved

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Last modified November 14 15:22 EST 2019. Contains 329126 sequences. (Running on oeis4.)