A376685 a(n) is the unique k such that A376637(k) is the reversal of A376637(n).

1, 2, 3, 5, 4, 6, 9, 10, 7, 8, 13, 15, 11, 16, 12, 14, 19, 21, 17, 23, 18, 24, 20, 22, 27, 28, 25, 26, 38, 34, 40, 33, 32, 30, 39, 37, 36, 29, 35, 31, 44, 43, 42, 41, 48, 47, 46, 45, 54, 53, 56, 55, 50, 49, 52, 51, 59, 60, 57, 58, 62, 61, 64, 63, 67, 68, 65

Offset: 1

Author

Rémy Sigrist, Oct 01 2024

Keywords

• nonn
• base

Comments

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

Examples

			The first terms, alongside the corresponding terms of A376637, are:
  n   a(n)  A376637(n)  A376637(a(n))
  --  ----  ----------  -------------
   1     1           1              1
   2     2           2              2
   3     3          11             11
   4     5          12             21
   5     4          21             12
   6     6          22             22
   7     9         112            211
   8    10         122            221
   9     7         211            112
  10     8         221            122
  11    13        1121           1211
  12    15        1122           2211
  13    11        1211           1121
  14    16        2122           2212
  15    12        2211           1122
  16    14        2212           2122
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10048
• Rémy Sigrist, PARI program
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A004086, A376637, A376686.

Programs

PARI

\\ See Links section.

Formula

A376637(a(n)) = A004086(A376637(n)).