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New Mersenne Prime discovered (probably)

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359 points sdsykes | 2 comments | 16 Oct 24 11:51 UTC | HN request time: 0s | source
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stevefan1999 ◴[19 Oct 24 06:39 UTC] No.41886077[source]▶
But why do we have to "discover" it when we know the formula would be 2^N - 1...? Are we trying to prove a corollary or what?
replies(2): >>41886104 #>>41886109 #
aaronmdjones ◴[19 Oct 24 06:45 UTC] No.41886104[source]▶
Not all 2^N - 1 are prime. For example, N=18 makes 2^N - 1 = 262143, which can also be written as 3^3 * 7 * 19 * 73 (not prime).
replies(2): >>41886111 #>>41887510 #
1. umanwizard ◴[19 Oct 24 12:56 UTC] No.41887510[source]▶
A lot simpler example is 2^4-1=5*3
replies(1): >>41890565 #
2. lupire ◴[19 Oct 24 20:32 UTC] No.41890565[source]▶
2^11-1 (prime power) for a less trivial example