allocate mem(2^30)

tr(v)=if (v>=0, 1+2*v, -2*v)
big = 100000
s = []
S = []
seen(z)=my (x=tr(real(z)),y=tr(imag(z)));if (max(x,y)>big, setsearch(S,z), x>#s, 0, bittest(s[x],y))
see(z)=my (x=tr(real(z)),y=tr(imag(z)));if (max(x,y)>big, S=setunion(S,Set(z)); return, x>#s, s=concat(s,vector(x-#s))); s[x]=bitor(s[x],2^y)

dz = [1, 1+I, I, I-1, -1, -1-I, -I, 1-I]
neighbours(z) = apply(d -> d+z, dz)

{
	print (0" "tot=0);

	gen = [0, 1];
	for (n=1, 2^13,
		print (n " " tot+=#gen);
		apply(see, gen);

		ngen = Set(concat(apply(neighbours, gen)));
		gen = select(z -> !seen(z) && vecsum(apply(seen, neighbours(z)))==2, ngen);
	);
}

quit