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A062239 Numbers n with property that every digit is a prime factor of n. 2

%I

%S 2,3,5,7,22,33,55,77,222,333,555,735,777,2222,2232,2322,2772,3222,

%T 3333,3555,5355,5535,5555,5775,7777,22222,22332,22722,23232,23322,

%U 23772,27272,32232,32322,33222,33333,33555,35355,35535,37737,53355,53535

%N Numbers n with property that every digit is a prime factor of n.

%C This is a regular language in base 10. Almost all members of this sequence are multiples of either 42 or 105. There are about 2/63 * 3^n members of this sequence up to 10^n. - _Charles R Greathouse IV_, Nov 09 2011

%H Harry J. Smith and Charles R Greathouse IV, <a href="/A062239/b062239.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Smith)

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>

%e 77322 is divisible by 7, 3 and 2.

%t Select[Range[2, 50000], Complement[IntegerDigits[#], FactorInteger[#][[All, 1]]] == {} &] (* _Alonso del Arte_, Dec 05 2011 *)

%o (PARI) { n=0; for (m=1, 10^10, t=m; b=1; while (t>0, d=t%10; t=(t-d)/10; if (!isprime(d) || m%d, b=0; break)); if (b, write("b062239.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Feb 17 2010

%K base,easy,nonn

%O 1,1

%A _Erich Friedman_, Jun 30 2001

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Last modified December 5 06:51 EST 2020. Contains 338944 sequences. (Running on oeis4.)