sequence: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/cmtk/bin/sequence - from package: cmtk

You may install the required package with command apt-get install {package}

Error in other languages:
sequence: bevel nie gevind nie
sequence: comandă negăsită
sequence: comando não encontrado
sequence: commande introuvable
sequence: command not found
sequence: käsku ei ole
sequence: không tìm thấy lệnh
sequence: komanda nerasta
sequence: Kommando nicht gefunden.
sequence: kommandot finns inte
sequence: komut yok
sequence: nie znaleziono polecenia
sequence: níor aimsíodh an t-ordú
sequence: no se encontró la orden
sequence: no s'ha trobat l'ordre
sequence: opdracht niet gevonden
sequence: parancs nem található
sequence: perintah tidak ditemukan
sequence: príkaz nenájdený
sequence: příkaz nenalezen
sequence: команда не найдена
sequence: командата не е открита
sequence: 命令找不到
sequence: コマンドが見つかりません