In the case of a man who became entitled to old-age insurance benefits and died before the month in which he attained retirement age (as defined in section 416( l ) of this title), the Commissioner of Social Security shall recompute his primary insurance amount as provided in subsection (a) as though he became entitled to old-age insurance benefits in the month in which he died; except that (i) his computation base years referred to in subsection (b)(2) shall include the year in which he died, and (ii) his elapsed years referred to in subsection (b)(3) shall not include the year in which he died or any year thereafter. Such recomputation of such primary insurance amount shall be effective for and after the month in which he died.