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++)

at knight distance(x,y) = vecsort(apply(abs, factor(x/y)[,2]~))==[1,2]

other(p) = {
	see(p);
	for (v=unseen, oo,
		if (!seen(v) && at knight distance(p,v),
			return (v);
		);
	);
}

v=1; for (n=1, 10 000, print (n " " v); v=other(v))

quit