A321464 Reverse nonzero digits in ternary expansion of n and convert back to decimal.

0, 1, 2, 3, 4, 7, 6, 5, 8, 9, 10, 19, 12, 13, 22, 21, 16, 25, 18, 11, 20, 15, 14, 23, 24, 17, 26, 27, 28, 55, 30, 31, 58, 57, 34, 61, 36, 37, 64, 39, 40, 67, 66, 49, 76, 63, 46, 73, 48, 43, 70, 75, 52, 79, 54, 29, 56, 33, 32, 59, 60, 35, 62, 45, 38, 65, 42, 41

Offset: 0

Author

Rémy Sigrist, Nov 10 2018

Keywords

• nonn
• base
• look

Comments

This sequence is a self-inverse permutation of nonnegative integers with fixed points A321473.

See A321474 for the decimal variant.

The binary variant simply corresponds to the identity (A001477).

Examples

			The first values at prime indices, alongside the corresponding ternary expansions, are:
  n   a(n)  ter(n)  ter(a(n))
  --  ----  ------  ---------
   2     2       2          2
   3     3      10         10
   5     7      12         21
   7     5      21         12
  11    19     102        201
  13    13     111        111
  17    25     122        221
  19    11     201        102
  23    23     212        212
  29    55    1002       2001
  31    31    1011       1011
  37    37    1101       1101
  41    67    1112       2111
  43    49    1121       1211
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..19683
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A001477, A004488, A030102, A321473, A321474.

Programs

Mathematica

a[n_] := Block[{x = IntegerDigits[n, 3], t}, t = Flatten@ Position[x, 1 | 2]; x[[Reverse@ t]] = x[[t]]; FromDigits[x, 3]]; Array[a, 68, 0] (* Giovanni Resta, Sep 17 2019 *)

PARI

a(n,base=3) = my (d=digits(n,base),t=Vecrev(select(sign,d)),i=0); for (j=1, #d, if (d[j], d[j] = t[i++])); fromdigits(d,base)

Formula

a(3 * n) = 3 * a(n).