A371268 If the ternary expansion of n starts with a 1, replace 1's by 2's, 2's by 0's, 0's by 1's, if it starts with a 2, replace 2's by 1's, 1's by 0's, 0's by 2's.

0, 2, 1, 7, 8, 6, 5, 3, 4, 22, 23, 21, 25, 26, 24, 19, 20, 18, 17, 15, 16, 11, 9, 10, 14, 12, 13, 67, 68, 66, 70, 71, 69, 64, 65, 63, 76, 77, 75, 79, 80, 78, 73, 74, 72, 58, 59, 57, 61, 62, 60, 55, 56, 54, 53, 51, 52, 47, 45, 46, 50, 48, 49, 35, 33, 34, 29, 27

Offset

0,2

Comments

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

Links

Rémy Sigrist, Table of n, a(n) for n = 0..6560

Index entries for sequences that are permutations of the natural numbers

Formula

A371256(a(n)) = A371256(n).

Example

The first terms, in decimal and in base 3, are:
  n   a(n)  ter(n)  ter(a(n))
  --  ----  ------  ---------
   0     0       0          0
   1     2       1          2
   2     1       2          1
   3     7      10         21
   4     8      11         22
   5     6      12         20
   6     5      20         12
   7     3      21         10
   8     4      22         11
   9    22     100        211
  10    23     101        212
  11    21     102        210
  12    25     110        221
  13    26     111        222
  14    24     112        220
  15    19     120        201

Prog

(PARI) a(n) = { my (d = digits(n, 3)); if (#d, d = if (d[1]==1, apply(v -> [1, 2, 0][1+v], d), apply(v -> [2, 0, 1][1+v], d)); ); fromdigits(d, 3); }

Crossrefs

See A004488 and A361945 for similar sequences.

Cf. A338246, A371256.

Sequence in context: A157240 A144749 A021463 * A371261 A199964 A217107

Adjacent sequences: A371265 A371266 A371267 * A371269 A371270 A371271

Keyword

nonn,base,easy

Author

Rémy Sigrist, Mar 16 2024

Status

approved