{
	a = vectorsmall(10 000);
	u = 1;

	f = [0];	\\ leading terms
	m = [0];	\\ multiples of leading terms

	for (d = 1, oo,
		for (k = 1, d,
			n = d+1-k;

			if (k==1,
				if (#f < n,
					f = concat(f, vector(#f));
					m = concat(m, vector(#m));
				);
				m[n] = f[n] = u;
			);

			while (m[n]<=#a && a[m[n]],
				m[n] += f[n];
			);

			if (m[n]<=#a,
				a[m[n]] = d*(d-1)/2+k;
				while (a[u],
					print (u " " a[u]);
					if (u++ > #a,
						break (3);
					);
				);
			);
		);
	);
}

quit