\usepackage{intcalc}
\usepackage{color}
\definecolor{gray}{RGB}{200,200,200}
-\newcounter{parnum}
+%\newcounter{parnum}
\newlength{\parnumwidth}
\setlength{\parnumwidth}{3em}
\newcommand{\N}{%
\ifnum\intcalcMod{\value{parnum}}{5}=0%
\marginnote{\textcolor{gray}{\small{\theparnum}}}%
\fi\reversemarginpar}
+\renewcommand{\N}{}
+\renewcommand{\Nw}{}
\newcommand{\akap}[1]{%
\par{\N#1}%