{
	a = vector(10 000);
	h = vector(2 * #a);
	for (n = 1, #a,
		\\ mask of horizontal constraints
		th = 0;
		for (k=n, 2*n-1,
			th = bitor(th, h[k]);
		);

		\\ mask of vertical constraints
		tv = if (n%2, 0, (2^(n/2)-1)*2^(a[n/2]-1));

		ch = 2^0 + 2^n;
		cv = 2^n-1;

		for (w=1, oo,
			if (bitand(th, ch)==0 && bitand(tv, cv)==0,
				print (n " " a[n] = w);
				for (k=n, 2*n-1,
					h[k] += ch;
				);
				break,
				ch *= 2;
				cv *= 2;
			);
		);
	);
}

quit