Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Jun 16 2018 13:44:14
%S 0,1,3,2,5,11,6,13,27,4,9,19,10,21,43,22,45,91,12,25,51,26,53,107,54,
%T 109,219,8,17,35,18,37,75,38,77,155,20,41,83,42,85,171,86,173,347,44,
%U 89,179,90,181,363,182,365,731,24,49,99,50,101,203,102,205,411
%N For any number n >= 0: apply the map 0 -> "0", 1 -> "01", 2 -> "011" to the ternary representation of n and interpret the result as a binary string.
%C This sequence is a ternary analog of A048678.
%C This sequence is a permutation of A003726.
%H Rémy Sigrist, <a href="/A305878/a305878.png">Colored logarithmic scatterplot of the first 3^10 terms</a> (where the color is function of A053735(n) + A081604(n))
%F a(0) = 0.
%F a(3*n) = 2*a(n).
%F a(3*n + 1) = 4*a(n) + 1.
%F a(3*n + 2) = 8*a(n) + 3.
%F A000120(a(n)) = A053735(n).
%e The first terms, alongside the ternary representation of n and the binary representation of a(n), are:
%e n a(n) tern(n) bin(a(n))
%e -- ---- ------- ---------
%e 0 0 0 0
%e 1 1 1 1
%e 2 3 2 11
%e 3 2 10 10
%e 4 5 11 101
%e 5 11 12 1011
%e 6 6 20 110
%e 7 13 21 1101
%e 8 27 22 11011
%e 9 4 100 100
%e 10 9 101 1001
%e 11 19 102 10011
%e 12 10 110 1010
%o (PARI) a(n) = if (n==0, 0, my (d=n%3); a(n\3) * 2^(d+1) + (2^d-1))
%Y Cf. A000120, A003726, A048678, A053735, A081604.
%K nonn,base
%O 0,3
%A _Rémy Sigrist_, Jun 13 2018