A372783 In the ternary expansion of n: keep the initial digit, and then replace 0's with 1's and 1's with 0's.

0, 1, 2, 4, 3, 5, 7, 6, 8, 13, 12, 14, 10, 9, 11, 16, 15, 17, 22, 21, 23, 19, 18, 20, 25, 24, 26, 40, 39, 41, 37, 36, 38, 43, 42, 44, 31, 30, 32, 28, 27, 29, 34, 33, 35, 49, 48, 50, 46, 45, 47, 52, 51, 53, 67, 66, 68, 64, 63, 65, 70, 69, 71, 58, 57, 59, 55, 54

Offset

0,3

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

a(n) = n iff n belongs to A062318.

Example

For n = 42: the ternary expansion of 42 is "1120", so the ternary expansion of a(42) is "1021", and a(42) = 34.

Mathematica

Table[t3=IntegerDigits[n, 3]; fd=First[t3]; tr=Rest[t3]/.{1->0, 0->1}; PrependTo[tr, fd]; FromDigits[tr, 3], {n, 0, 67}] (* James C. McMahon, May 31 2024 *)

Prog

(PARI) a(n) = { my (t = digits(n, 3)); for (i = 2, #t, t[i] = [1, 0, 2][1+t[i]]; ); fromdigits(t, 3); }

Crossrefs

Cf. A004488, A062318 (fixed points), A115303.

Sequence in context: A372341 A166014 A357527 * A348357 A199779 A374800

Adjacent sequences: A372780 A372781 A372782 * A372784 A372785 A372786

Keyword

nonn,base,look,easy

Author

Rémy Sigrist, May 13 2024

Status

approved