Це щось типу такого?
\begin{longtable}
{|c|c|c|c|c|c|c|c|c|} a & a & a & a & a & a & a & a & a \kill
\hline \raisebox{-1.50ex}[0cm][0cm]{ $n$}& \multicolumn{3}{|c|}{
$\gamma$} & {} & \raisebox{-1.50ex}[0cm][0cm]{{ $n$}{} }&
\multicolumn{3}{|c|}{$\gamma$} \\
\cline{2-5} \cline{7-9}
&
$0,95$& $0,99$& $0,999$& {} &
&
$0,95$& $0,99$&
$0,999$ \\
\hline $5$ & $2,78$ & $4,60$ & $8,61$ & & $20$ & $2,093$ & $2,861$
& $3,883$ \\
$6$ & $2,57$ & $4,03$ & $6,86$ & & $25$ & $2,064$ & $2,797$ &
$3,745$ \\
$7$ & $2,45$ & $3,71$ & $5,96$ & & $30$ & $2,045$ & $2,756$ &
$3,659$ \\
$8$ & $2,37$ & $3,50$ & $5,41$ & & $35$ & $2,032$ & $2,720$ &
$3,600$ \\
$9$ & $2,31$ & $3,36$ & $5,04$ & & $40$ & $2,023$ & $2,708$ &
$3,558$ \\
$10$ & $2,26$ & $3,25$ & $4,78$ & & $45$ & $2,016$ & $2,692$ &
$3,527$ \\
$11$ & $2,23$ & $3,17$ & $4,59$ & & $50$ & $2,009$ & $2,679$ &
$3,502$ \\
$12$ & $2,20$ & $3,11$ & $4,44$ & & $60$ & $2,001$ & $2,662$ &
$3,464$ \\
$13$ & $2,18$ & $3,06$ & $4,32$ & & $70$ & $1,996$ & $2,649$ &
$3,439$ \\
$14$ & $2,16$ & $3,01$ & $4,22$ & & $80$ & $1,991$ & $2,640$ &
$3,418$ \\
$15$ & $2,15$ & $2,98$ & $4,14$ & & $90$ & $1,987$ & $2,633$ &
$3,403$ \\
$16$ & $2,13$ & $2,95$ & $4,07$ & & $100$ & $1,984$ & $2,627$ &
$3,392$ \\
$17$ & $2,12$ & $2,92$ & $4,02$ & & $120$ & $1,980$ & $2,617$ &
$3,374$ \\
$18$ & $2,11$ & $2,90$ & $3,97$ & & $\infty$ & $1,960$ & $2,576$ &
$3,291$ \\
$19$ & $2,10$ & $2,88$ & $3,92$ & & & & & \\
\hline
\end{longtable}