%I #22 Nov 28 2015 13:45:22
%S 1,2,0,0,3,4,9,8,0,5,10,0,7,6,0,0,11,0,0,23,24,13,12,0,0,22,0,25,14,0,
%T 17,18,0,21,26,0,0,15,16,0,19,20,0,27,28,69,68,0,0,0,0,0,0,0,29,70,0,
%U 67,0,0,0,0,0,31,30,0,0,71,66,0,0,0,0,0,32,0,35,36
%N Sierpiński arrowhead curve as a triangular array starting leftward from the top, read by rows.
%C The triangle up to the (1 + 2^n)th row is the n-th iteration of the curve, rotated such that the curve begins at the top and continues down to the left.
%C As this is not a space-filling curve, not all points on the triangular lattice are reached by the curve; these points are given the value 0.
%H Max Barrentine, <a href="/A262174/b262174.txt">Table of n, a(n) for n = 1..2144</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Sierpi%C5%84ski_arrowhead_curve">Sierpiński arrowhead curve</a>
%e The first 5 rows of this triangle show how this curve begins (connect the terms in numerical order):
%e 1;
%e 2, 0;
%e 0, 3, 4;
%e 9, 8, 0, 5;
%e 10, 0, 7, 6, 0;
%e ...
%Y See also A163357, A163334, and A054238 for other fractal curves.
%K nonn,tabl,look
%O 1,2
%A _Max Barrentine_, Sep 13 2015