A046503 Primes with multiplicative persistence value 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

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