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A262174 Sierpiński arrowhead curve as a triangular array starting leftward from the top, read by rows.

%I A262174 #22 Nov 28 2015 13:45:22
%S A262174 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 A262174 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 A262174 67,0,0,0,0,0,31,30,0,0,71,66,0,0,0,0,0,32,0,35,36
%N A262174 Sierpiński arrowhead curve as a triangular array starting leftward from the top, read by rows.
%C A262174 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 A262174 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 A262174 Max Barrentine, <a href="/A262174/b262174.txt">Table of n, a(n) for n = 1..2144</a>
%H A262174 Wikipedia, <a href="https://en.wikipedia.org/wiki/Sierpi%C5%84ski_arrowhead_curve">Sierpiński arrowhead curve</a>
%e A262174 The first 5 rows of this triangle show how this curve begins (connect the terms in numerical order):
%e A262174             1;
%e A262174           2,  0;
%e A262174         0,  3,  4;
%e A262174       9,  8,  0,  5;
%e A262174    10,  0,  7,  6,  0;
%e A262174    ...
%Y A262174 See also A163357, A163334, and A054238 for other fractal curves.
%K A262174 nonn,tabl,look
%O A262174 1,2
%A A262174 _Max Barrentine_, Sep 13 2015