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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 (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 Table of n, a(n) for n=1..31. 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 A140467 Sequence in context: A263926 A114788 A085074 * A110404 A366529 A190366 Adjacent sequences: A175634 A175635 A175636 * A175638 A175639 A175640 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

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Last modified December 3 03:10 EST 2023. Contains 367531 sequences. (Running on oeis4.)