  In a local Cohen-Macaulay ring $(A, \mathrm{m})$, we study the Hilbert
function of an $\mathrm{m}$-primary ideal $I$ whose reduction number is two. It
is a continuous work of the papers of Huneke, Ooishi, Sally, and
Goto-Nishida-Ozeki. With some conditions, we show the inequality
$\mathrm{e}_1(I)\ge \mathrm{e}_0(I) - \ell_A (A/I) + \mathrm{e}_2(I)$ of the
Hilbert coefficients, which is the converse inequality of Sally and Itoh. We
also study relations between the Hilbert coefficients and the depth of the
associated graded ring.
