{
	\\ upper left triangle
	tri = vector(500, k, Set());

	for (n=1, #tri,
		if (n%2==0,
			tri[n] = tri[n/2],
			for (w=1, oo,
				my (f=1/n, s=Set());
				if (f==1, f=f/2);
				while (!setsearch(s,f),
					i = floor(f*2^w);
					if (i,
						tri[n] = setunion(tri[n],Set(i));
					);
					s = setunion(s,Set(f));
					f=frac(f*2);
				);
				if (#tri[n] >= #tri+1-n,
					break;
				);
			);
		);
	);

	\\ antidiagonals flattened
	i = 0;
	for (d=1, #tri,
		for (k=1, d,
			print (i++ " " tri[d+1-k][k]);
		);
	);
}

quit