s = 0
seen(v) = bittest(s, v)
see(v) = s = bitor(s, 2^v)

a = vector(8192, n, -1)
u = 0

T = vector(1911)
n = 0
m = -1
emit(t) = {
	if (n++ <= #T,
		T[n] = t;
	);
	for (k = 1, #t,
		if (!seen(t[k]),
			see(t[k]);
			a[1+t[k]] = m++;
		);
	);

	while (a[1+u]>=0,
		print (u " " a[1+u]);
		if (u++ == #a,
			quit;
		);
	);
}

{
	emit([0, 1]);
	for (k = 1, #T,
		my (t = T[k]);

		if (#t > 1,
			emit(2*t[2..#t]);
		);
		emit(concat(
			[2*t[1]+0, 2*t[1]+1],
			[2*v+1 | v <- t[2..#t]]
		));
	);
}

quit