A023802 Xenodromes: all digits in base 7 are different.

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, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 51, 52, 53, 54, 55, 63, 66, 67, 68, 69, 70, 72, 74, 75, 76, 77, 79, 80, 82, 83, 84, 86, 87, 88, 90

Offset

1,3

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..11743 (full sequence)

Example

4146 in base 7 is 15042. Since no two digits of the base 7 representation are the same, 4146 is in the sequence.
4147 in base 7 is 15043. Since no two digits of the base 7 representation are the same, 4147 is in the sequence.
4148 in base 7 is 15044. Since the digit 4 appears twice in the base 7 representation, 4148 is not in the sequence.

Mathematica

Select[Range[0, 97], Max[DigitCount[#, 7]] == 1 &] (* Alonso del Arte, Feb 09 2019 *)

Prog

(PARI) isok(n) = my(d=digits(n, 7)); #d == #Set(d); \\ Michel Marcus, Feb 09 2019

Crossrefs

Cf. A023798 - A023810.

Cf. A007093 (numbers in base 7).

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

Sequence in context: A187320 A255805 A043093 * A007915 A377019 A344742

Adjacent sequences: A023799 A023800 A023801 * A023803 A023804 A023805

Keyword

nonn,base,fini,full,easy

Author

Olivier Gérard

Status

approved