\\ n -> "digits" (least significant first)
encode(n) = {
	my (d=[]);
	for (r=2, oo,
		if (n==0,
				return (d),
				d = concat(d, n%r);
				n\=r;
		);
	);
}

\\ "digits" -> n
decode(d) = {
	sum(k=1, #d, d[k]*k!)
}

\\ lunar addition
A(n, k) = {
	my (nn=encode(n), kk=encode(k));
	decode(vector(max(#nn, #kk), i, max(if (i<=#nn, nn[i], 0), if (i<=#kk, kk[i], 0))))
}

\\ lunar multiplication
M(n, k) = {
	my (nn=encode(n), kk=encode(k), vv=vector(max(0, #nn+#kk-1)));
	for (i=1, #nn,
		for (j=1, #kk,
			vv[i+j-1] = max(vv[i+j-1], min(nn[i], kk[j]));
		);
	);
	decode(vv);
}

a(n) = M(n, n)

for (n=0, 7!-1, print (n " " a(n)))

quit