%I
%S 1,2,3,6,5,4,7,8,9,12,11,10,13,14,15,18,17,16,19,20,21,24,23,22,25,26,
%T 27,30,29,28,31,32,33,36,35,34,37,38,39,42,41,40,43,44,45,48,47,46,49,
%U 50,51,54,53,52,55,56,57,60,59,58,61,62,63,66,65,64,67,68,69,72,71,70
%N a(6n) = 6n+1, a(6n+1) = 6n+2, a(6n+2) = 6n+3, a(6n+3) = 6n+6, a(6n+4) = 6n+5, a(6n+5) = 6n+4.
%t Table[6n+{1,2,3,6,5,4},{n,0,20}]//Flatten (* _Harvey P. Dale_, Sep 30 2016 *)
%K nonn
%O 0,2
%A _Paul Curtz_, Oct 15 2007
