A375755 Lexicographically earliest sequence of distinct positive integers such that two consecutive terms have different initial digits.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 11, 21, 12, 22, 13, 23, 14, 24, 15, 25, 16, 26, 17, 27, 18, 28, 19, 29, 30, 40, 31, 41, 32, 42, 33, 43, 34, 44, 35, 45, 36, 46, 37, 47, 38, 48, 39, 49, 50, 60, 51, 61, 52, 62, 53, 63, 54, 64, 55, 65, 56, 66, 57, 67, 58, 68

Offset

1,2

Comments

This sequence is a permutation of the positive integers with inverse A375756.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, PARI program

Index entries for sequences that are permutations of the natural numbers

Formula

A000030(a(n)) <> A000030(a(n+1)).

Example

The first terms, alongside the corresponding initial digits, are:
  n   a(n)  Initial digit
  --  ----  -------------
   1     1              1
   2     2              2
   3     3              3
   4     4              4
   5     5              5
   6     6              6
   7     7              7
   8     8              8
   9     9              9
  10    10              1
  11    20              2
  12    11              1
  13    21              2
  14    12              1
  15    22              2

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A000030, A375756 (inverse), A375757.

Sequence in context: A264979 A319726 A302589 * A210538 A247143 A257128

Adjacent sequences: A375752 A375753 A375754 * A375756 A375757 A375758

Keyword

nonn,base,easy

Author

Rémy Sigrist, Aug 26 2024

Status

approved