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A046506 Primes with multiplicative persistence value 6.

%I A046506 #15 Feb 16 2025 08:32:39
%S A046506 8867,23887,27883,28387,28837,32887,34487,34847,38287,38447,43487,
%T A046506 44647,46447,47843,48437,48473,49999,72883,74843,78283,78823,82387,
%U A046506 82837,84347,84437,87443,88237,88327,94999,118687,123887,126487,128467
%N A046506 Primes with multiplicative persistence value 6.
%H A046506 Robert Israel, <a href="/A046506/b046506.txt">Table of n, a(n) for n = 1..10000</a>
%H A046506 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence</a>
%e A046506 8867 -> [ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in six steps.
%p A046506 filter:= proc(n) local L,i;
%p A046506   L:= convert(convert(n,base,10),`*`); if L < 10 then return false fi;
%p A046506   for i from 2 to 5 do
%p A046506      L:= convert(convert(L,base,10),`*`); if L < 10 then return false fi
%p A046506     od;
%p A046506   L:= convert(convert(L,base,10),`*`); evalb(L < 10)
%p A046506 end proc:
%p A046506 count:= 0: Res:= NULL;
%p A046506 p:= 11:
%p A046506 while count < 100 do
%p A046506   p:= nextprime(p);
%p A046506   if filter(p) then count:= count+1; Res:= Res,p fi
%p A046506 od:
%p A046506 Res; # _Robert Israel_, Jun 06 2018
%Y A046506 Cf. A046500, A046515.
%K A046506 nonn,base
%O A046506 1,1
%A A046506 _Patrick De Geest_, Sep 15 1998
%E A046506 Offset corrected by _Robert Israel_, Jun 06 2018