A375757 Lexicographically earliest sequence of distinct positive integers such that for any n > 0, n and a(n) have different initial digits.

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

Offset

1,1

Comments

This sequence is a self-inverse permutation of the positive integers.

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

Example

The first terms, alongside the corresponding initial digits, are:
  n   a(n)  A30(n)  A30(a(n))
  --  ----  ------  ---------
   1     2       1          2
   2     1       2          1
   3     4       3          4
   4     3       4          3
   5     6       5          6
   6     5       6          5
   7     8       7          8
   8     7       8          7
   9    10       9          1
  10     9       1          9
  11    20       1          2
  12    21       1          2
  13    22       1          2
  14    23       1          2
  15    24       1          2

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A000030, A375755.

Sequence in context: A137805 A163501 A306229 * A096779 A243500 A026262

Adjacent sequences: A375754 A375755 A375756 * A375758 A375759 A375760

Keyword

nonn,base,easy

Author

Rémy Sigrist, Aug 26 2024

Status

approved