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Xenodromes: all digits in base 7 are different.
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%I #20 Feb 22 2019 06:02:55

%S 0,1,2,3,4,5,6,7,9,10,11,12,13,14,15,17,18,19,20,21,22,23,25,26,27,28,

%T 29,30,31,33,34,35,36,37,38,39,41,42,43,44,45,46,47,51,52,53,54,55,63,

%U 66,67,68,69,70,72,74,75,76,77,79,80,82,83,84,86,87,88,90

%N Xenodromes: all digits in base 7 are different.

%H Nathaniel Johnston, <a href="/A023802/b023802.txt">Table of n, a(n) for n = 1..11743</a> (full sequence)

%e 4146 in base 7 is 15042. Since no two digits of the base 7 representation are the same, 4146 is in the sequence.

%e 4147 in base 7 is 15043. Since no two digits of the base 7 representation are the same, 4147 is in the sequence.

%e 4148 in base 7 is 15044. Since the digit 4 appears twice in the base 7 representation, 4148 is not in the sequence.

%t Select[Range[0, 97], Max[DigitCount[#, 7]] == 1 &] (* _Alonso del Arte_, Feb 09 2019 *)

%o (PARI) isok(n) = my(d=digits(n, 7)); #d == #Set(d); \\ _Michel Marcus_, Feb 09 2019

%Y Cf. A023798 - A023810.

%Y Cf. A007093 (numbers in base 7).

%Y Cf. A044956 (includes a subset of the complement of this sequence).

%K nonn,base,fini,full,easy

%O 1,3

%A _Olivier GĂ©rard_