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A175637
Numbers n such that the decimal digits of n are not present in k*n, k=2..9.
0
1, 3, 7, 9, 11, 77, 111, 707, 777, 909, 1111, 7777, 11111, 70707, 77777, 90909, 111111, 777777, 1111111, 7070707, 7777777, 9090909, 11111111, 77777777, 111111111, 707070707, 777777777, 909090909, 1111111111, 7777777777, 11111111111
OFFSET
1,2
COMMENTS
There are four infinite patterns 1..1, 7..7, 7070..7 & 9090..9.
EXAMPLE
7777*(1..9)= 7777,15554,23331,31108,38885,46662,54439,62216,69993.
MATHEMATICA
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
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Aug 01 2010
EXTENSIONS
Corrected and extended the sequence, changed the comment line and added the Mathematica coding Robert G. Wilson v, Aug 03 2010
STATUS
approved