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Old 2020-07-08, 16:27   #18
sweety439
 
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Nov 2016

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Originally Posted by sweety439 View Post
This page is only for the twin case and the Riesel case, for the Sierpinski case, see http://harvey563.tripod.com/cunninghams.txt

An interesting one is k=279, there is no known twin prime (k*2^n-1 and k*2^n+1), neither known 1st kind Sophie-Germain prime/Cunningham chain (k*2^n-1 and k*2^(n+1)-1) or known 2nd kind Sophie-Germain prime/Cunningham chain (k*2^n+1 and k*2^(n+1)+1)

Twin prime: CK=237
1st kind Sophie-Germain prime/Cunningham chain: CK=807
2nd kind Sophie-Germain prime/Cunningham chain: CK=32469
There is no known twin prime for some even k divisible by 3, e.g. k=312 (since all n must be >=1)
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