tozeck(n) = {
	for (i=0, oo,
		if (n<=fibonacci(2+i),
			my (v=0, f);
			forstep (j=i, 0, -1,
				if (n>=f=fibonacci(2+j),
					n-=f;
					v+=2^j;
				);
				if (n==0,
					return (v);
				);
			);
		);
	);
}

fromzeck(n) = {
	my (v=0, j);
	while (n,
		n-=2^j=valuation(n,2);
		v+=fibonacci(2+j);
	);
	return (v);
}

todualzeck(n) = {
	my (s=0, v=0);
	for (i=0, oo,
		if (s>=n,
			forstep (j=i-1, 0, -1,
				if (s-fibonacci(2+j)>=n,
					s-=fibonacci(2+j);
					v-=2^j;
				);
			);
			return (v);
		);
		s+=fibonacci(2+i);
		v+=2^i;
	);
}

a(n) = fromzeck(bitand(tozeck(n), todualzeck(n)))

for (n=0, fibonacci(21), print (n " " a(n)))

quit