A137305 Write n in base 3, change twos in ones and ones in twos, reverse.

0, 2, 1, 2, 8, 5, 1, 7, 4, 2, 20, 11, 8, 26, 17, 5, 23, 14, 1, 19, 10, 7, 25, 16, 4, 22, 13, 2, 56, 29, 20, 74, 47, 11, 65, 38, 8, 62, 35, 26, 80, 53, 17, 71, 44, 5, 59, 32, 23, 77, 50, 14, 68, 41, 1, 55, 28, 19, 73, 46, 10

Offset: 0

Author

Jonathan Vos Post, Apr 20 2008

Keywords

• base
• easy
• nonn

Comments

This is not to A036044 as A007089 is to A007088: despite similarity here the operation performed is not a base 3 complement. Fixed points begin: 5, 7, 11, 19, 29, 44, 50, 55.

Examples

			53 -> 1222 -> 2111 -> 1112 -> 41.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..6561

Crossrefs

Cf. A007089, A036044.

Programs

Maple

a:= proc(n) local m, r; m, r:= n, 0; while m>0
      do r:=r*3+[0, 2, 1][1+irem(m, 3, 'm')] od; r
    end:
seq(a(n), n=0..100);  # Alois P. Heinz, Jun 20 2016

Mathematica

a[n_] := FromDigits[ Reverse[ IntegerDigits[n, 3] /. {1 -> 2, 2 -> 1}], 3] (* Giovanni Resta, Jun 20 2016 *)

Formula

a(3^n) = 2. a(2*3^n) = 1.

Extensions

Edited and corrected by Giovanni Resta, Jun 20 2016