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Originally Posted by Batalov
Technically, this series is not as fast as Mersenne's (wall clock wise)

True, and Mersenne numbers also benefit a lot from algebraic factorizations that are not available here. I wasn't really thinking of this is as a contender for largest known prime, though there is an outside chance of breaking 17orbust's longstanding record for the largest nonMersenne prime (we'd need two more terms).
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I'll double check your terms with PFGW and scripts. I'll start with writing a quickanddirty sieve, maybe tonight.

Thanks. I can also send the certificate file if you like. I've recorded the factors found by sieving, so you don't have to repeat every step from scratch (unless you want to, of course)...