sequin: 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/bin/sequin - from package: ncbi-tools-x11

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

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