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 A128173 Numbers in ternary Gray code order. 3

%I

%S 0,1,2,5,4,3,6,7,8,17,16,15,12,13,14,11,10,9,18,19,20,23,22,21,24,25,

%T 26,53,52,51,48,49,50,47,46,45,36,37,38,41,40,39,42,43,44,35,34,33,30,

%U 31,32,29,28,27,54,55,56,59,58,57,60,61,62,71,70,69,66,67,68,65,64,63,72

%N Numbers in ternary Gray code order.

%H Alois P. Heinz, <a href="/A128173/b128173.txt">Table of n, a(n) for n = 0..19682</a>

%H Z. Sunic, <a href="http://arXiv.org/abs/math.CO/0612080">Tree morphisms, transducers and integer sequences</a>

%p A128173 := proc(nmax) local K,tmp,n3,n,r,c,t,a ; n3 := 3 ; n := 1 ; K := linalg[matrix](n3,1,[[0],[1],[2]]) ; while n3 < nmax do n3 := n3*3 ; n := n+1 ; tmp := K ; K := linalg[extend](K,2*n3/3,1,0) ; K := linalg[copyinto](tmp,K,1+n3/3,1) ; K := linalg[copyinto](tmp,K,1+2*n3/3,1) ; for r from 1 to n3 do K[r,n] := floor((r-1)/(n3/3)) ; od ; for r from n3/3+1 to n3/2 do for c from 1 to n do t := K[r,c] ; K[r,c] := K[n3+1-r,c] ; K[n3+1-r,c] := t ; od ; od ; od ; a := [] ; for r from 1 to n3 do a := [op(a), add( K[r,c]*3^(c-1),c=1..n) ] ; od ; a ; end: A128173(30) ; # _R. J. Mathar_, Jun 17 2007

%Y Cf. A003188, A105529, A105530.

%K nonn

%O 0,3

%A _Ralf Stephan_, May 09 2007

%E More terms from _R. J. Mathar_, Jun 17 2007

%E Offset changed to 0 by _Alois P. Heinz_, Feb 23 2018

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Last modified October 15 00:14 EDT 2019. Contains 328025 sequences. (Running on oeis4.)