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Old 2020-10-29, 16:32   #400
Dr Sardonicus
 
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Feb 2017
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The Main tables for the Cunningham Project give all that is known as of October 13, 2020 for 2^n - 1 and 2^n + 1, odd n < 1300; 2^n + 1, n = 4k-2, n < 2600; and 2^n + 1, n = 4k, n <= 1300.

I'm not sure about what's known for n > 1300, apart from factors found for specific reasons, as in this thread.
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