Generate set of unique 16 digits number/codes like recharge card/voucher using algorithm : <p>I have a task, where i need to Generate set of unique 16 digits number/codes like recharge card/voucher using algorithm.(like recharge scratch cards)</p>

<p>I have no idea on how to do this or which algorithm to use.</p>

<p>Please help/guide me in achieving this task.</p>

<p>Thanks in advance.</p>
