

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
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

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


LINKS



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



EXTENSIONS

Corrected and extended the sequence, changed the comment line and added the Mathematica coding Robert G. Wilson v, Aug 03 2010


STATUS

approved



