big = 1 000 000
s = 0
S = []
unseen = 1
seen(v) = if (v < big, bittest(s, v), setsearch(S, v))
see(v) = if (v < big, s = bitor(s, 2^v), S = setunion(S, [v])); while (seen(unseen), unseen++)

a = [0]
n = 0

b = vector(10 000)
u = 1

emit(v) = {
	n++;
	see(v);

	if (v <= #b,
		b[v] = n;
		while (b[u],
			print (u " " b[u]);
			if (u++ > #b,
				quit;
			);
		);
	);

	if (n > #a,
		a = concat(a, vector(#a));
	);

	a[n] = v;
}

other(p) = {
	for (v = unseen, oo,
		if (!seen(v) && (p==1 || gcd(p, v)!=1),
			return (v);
		);
	);
}

{
	emit(1);

	for (k = 1, oo,
		emit(other(a[k]));
		emit(other(a[k]));
	);
}

quit