Psequin: 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/Psequin - from package: ncbi-tools-x11

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

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