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) = {
	for (v=unseen, oo,
		if (!seen(v) && isprime(bitxor(p,v)),
			return (v);
		);
	);
}

{
	pp = 0;
	p = 0;
	for (n=1, 10 000,
		if (n==1, v = 1,
		    n==2, v = 2,
		          v = other(bitxor(pp,p)));
		see(v);
		print (n " " v);
		pp = p;
		p = v;
	);
}

quit