big = 1 000 000
s = 0
S = Set([])
unseen = 1
seen(v) = if (v < big, bit test(s, v), set search(S, v))
see(v) = if (v < big, s = bit or(s, 2^v), S = set union(S, Set([v]))); while (seen(unseen), unseen++)

other(p) = {
	forstep (m=2*p, oo, p,
		if (!seen(m),
			return (m);
		);
	);
}

n=0
a = vector(2^13)
emit(v) = {
	see(v);
	print (n++ " " a[n]=v);
}

{
	emit(1);
	while (n<#a,
		w=n;
		forstep (k=w, 1, -1,
			emit(other(a[k]));
		);
	);
}

quit