mersenneforum.org The dual Sierpinski/Riesel problem
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2017-11-26, 23:10   #12
sweety439

Nov 2016

282010 Posts

Quote:
 Originally Posted by sweety439 Reserve 305^n-2 to n=20000.
305^n-2 tested to n=20000, no (probable) prime found.

Reserve it to n=30000.
Attached Files
 base 305 status.txt (349.8 KB, 238 views)

2017-12-01, 21:56   #13
sweety439

Nov 2016

22·3·5·47 Posts

305^n-2 tested to n=30000, no (probable) prime found.

Base released.
Attached Files
 base 305 status.txt (351.7 KB, 236 views)

 2020-12-23, 23:56 #14 sweety439   Nov 2016 22×3×5×47 Posts In fact, if x*y = b, then x*b^n+1 is the dual of y*b^n+1 x*b^n-1 is the dual of y*b^n-1 (x*b^n+1)/gcd(x+1,b-1) is the dual of (y*b^n+1)/gcd(y+1,b-1) (x*b^n-1)/gcd(x-1,b-1) is the dual of (y*b^n-1)/gcd(y-1,b-1) Thus they have the same weight
 2021-02-15, 15:58 #15 sweety439   Nov 2016 22×3×5×47 Posts Since 2293*2^12918431-1 is known to be prime (see post https://mersenneforum.org/showpost.p...&postcount=895), the only 4 remain odd k<509203 with neither known prime of the form k*2^n-1 nor known (probable) prime of the form |2^n-k| are 342847, 344759, 386801, 444637 Also, the "mixed Sierpinski conjecture base 5" is now a theorem (in the weak case that probable primes are allowed), see thread https://mersenneforum.org/showthread.php?t=26328, the only even k<159986 not divisible by 5 with neither known prime of the form k*5^n+1 nor known proven prime of the form 5^n+k is 31712, and there is known probable prime for k=31712: 5^50669+31712

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