What others have told you here is correct: when you terminated your contract with Cogent [any contract language nonwithstanding] you gave up your "right" to use any portion of their address space.
As one person on here already pointed out, this is a good thing. Think about it.
What it tells me is I should have wasted enough space to consume 8 /24s long ago, so I could get a /20 directly from ARIN. I assign IPs to customers very conservatively. Multiple DSL customers with static IPs are put on a shared subnet instead of one subnet per customer. I easily could have used 8 /24's a year ago and still conformed to ARIN rules. At the time I was only using 3 /24's. We recently reached 8 /24s and applied to ARIN a few weeks ago for a /20, but it sounds like the best thing to do is to use IPs in the most inefficient way possible (while still conforming to ARIN policy) in order to quickly qualify for PI space. -Ralph