A376686 a(n) is the unique k such that A376677(k) is the reversal of A376677(n), or -1 if no such k exists.

1, 2, 3, 5, 4, 6, 10, 8, 12, 7, 11, 9, 15, 21, 13, 19, 17, 18, 16, 22, 14, 20, 23, 32, 28, 30, 35, 25, 33, 26, 34, 24, 29, 31, 27, 36, 46, 53, 50, 40, 52, 44, 48, 42, 54, 37, 49, 43, 47, 39, 51, 41, 38, 45, 60, 76, 66, 63, 79, 55, 71, 65, 58, 74, 62, 57, 67

Offset: 1

Author

Rémy Sigrist, Oct 01 2024

Keywords

• nonn
• base

Comments

Is this sequence a permutation of the positive integers?

Examples

			The first terms, alongside the corresponding terms of A376677, are:
  n   a(n)  A376677(n)  A376677(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    10         112            211
   8     8         121            121
   9    12         122            221
  10     7         211            112
  11    11         212            212
  12     9         221            122
  13    15        1121           1211
  14    21        1122           2211
  15    13        1211           1121
  16    19        1212           2121
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10304
• Rémy Sigrist, PARI program
• Index entries for sequences related to Kolakoski sequence

Crossrefs

Cf. A000002, A376677, A376685.

Programs

PARI

\\ See Links section.