$servers = Get-Content C:\DataDir\servers.txt
$kolla = $null
$utfil = "C:\DataDir\outfile.csv"
foreach($server in $servers)
{
    $kolla = get-adcomputer $server -Properties lastlogontimestamp -erroraction silentlycontinue
    if ($kolla -eq $null)
    {
        write-output "$server;Nej" | out-file $utfil -Append
    }
    else
    {
    write-output "$server;$((get-date $kolla.lastlogontimestamp).AddYears(1600).ToShortDateString())" | out-file $utfil -Append
    }
    $kolla = $null
}