In xml file write :

<record id="seq_type_1" model="ir.sequence.type"> <field name="name">Test Type</field> <field name="code">test</field> </record> <record id="seq_1" model="ir.sequence"> <field name="name">Test</field> <field name="code">test</field> <field name="prefix">test</field> <field name="padding">3</field> </record>

In .py file all default in object where you want to add sequence :

_defaults = { 'x_opp_num': lambda obj, cr, uid, context: obj.pool.get('ir.sequence').get(cr, uid, 'test'), }

In default 'test' is same name as code in xml.