ab = vector(10 000)
nw = vector(#ab)

{
	k = -1;
	for (s=1, #ab,
		sw = 0;
		for (c=1, s,
			x = bitor(ab[c], bitor(nw[s-c+1], sw));
			v = valuation(x+1, 2);

			if (c==s,
				print (k++ " " v);
			);

			p = 2^v;
			sw += p;
			ab[c] += p;
			nw[s-c+1] += p;
		);
	);
}

quit