upto(n) = {
	n++;
	my(v = vector(n), res = List(), streak = 1);
	for(i = 1, sqrtint(n), 
		t = 0;
		forstep(j = i, 1, -1,
			t+=j^2;
			if(t <= n,
				v[t] = 1
			,
				next(2)
			)
		)
	);
	for(i = 1, n,
		if(v[i] == 1,
			streak++;
			if(streak >= 3,
				listput(res, i-2)
			)
		,
			streak = 0
		)
	);
	res
}