I had around 4k bas from mining in July 2017 ... should I keep and wait ?? 
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...You're late late - the coin was swapped for a ERC token long time ago
Wow 4,000 Bitasean coins pre-swap? Where were you when the swap happened? I think the swap happened around July or late June and you were not informed nor have no idea that it is being swapped for an ERC20 token. See if you can still be able to make the swap with the admin.