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A175637 Numbers n such that the decimal digits of n are not present in k*n, k=2..9. 0

%I #6 Apr 19 2013 08:58:45

%S 1,3,7,9,11,77,111,707,777,909,1111,7777,11111,70707,77777,90909,

%T 111111,777777,1111111,7070707,7777777,9090909,11111111,77777777,

%U 111111111,707070707,777777777,909090909,1111111111,7777777777,11111111111

%N Numbers n such that the decimal digits of n are not present in k*n, k=2..9.

%C There are four infinite patterns 1..1, 7..7, 7070..7 & 9090..9.

%e 7777*(1..9)= 7777,15554,23331,31108,38885,46662,54439,62216,69993.

%t fQ[n_] := Intersection[ IntegerDigits@n, Union@ Flatten[ IntegerDigits[n* Range[2, 9]]]] == {}; k = 1; lst = {}; While[k < 10^9, If[ fQ@k, AppendTo[lst, k]]; k++ ]; lst

%Y A140467

%K base,nonn

%O 1,2

%A _Zak Seidov_, Aug 01 2010

%E Corrected and extended the sequence, changed the comment line and added the Mathematica coding _Robert G. Wilson v_, Aug 03 2010

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Last modified March 4 22:06 EST 2024. Contains 370532 sequences. (Running on oeis4.)