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Numbers k such that the digits of k are not present in 3k.
1

%I #6 Mar 02 2019 23:39:18

%S 1,2,3,4,6,7,8,9,11,12,16,18,19,21,22,23,26,27,29,32,33,34,36,37,38,

%T 39,43,44,46,54,58,59,63,64,66,67,68,69,73,74,76,77,78,81,83,84,87,88,

%U 89,91,94,96,108,109,111,112,116,118,119,121,122,126,129,136,158,159,161

%N Numbers k such that the digits of k are not present in 3k.

%e 169 is in the sequence because the sets {1,6,9} and {5,0,7} are disjoint.

%p a:=proc(n) local nd, n3d: nd:=convert(convert(n,base,10),set): n3d:=convert(convert(3*n,base,10),set): if `intersect`(nd, n3d)={} then n else end if end proc: seq(a(n),n=1..170); # _Emeric Deutsch_, Jul 20 2008

%t Select[Range[200],Intersection[IntegerDigits[#],IntegerDigits[3*#]]=={}&] (* _Harvey P. Dale_, Aug 13 2018 *)

%K nonn,base,easy

%O 1,2

%A Jonathan Vos Post, Jun 25 2008

%E More terms from _Emeric Deutsch_, Jul 20 2008