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Old 2020-07-21, 03:28   #23
sweety439's Avatar
Nov 2016

22·32·5·13 Posts

Originally Posted by kar_bon View Post
There're two problems with the example of 13*43^n-1:

1. All candidates are divisible by 6.
2. The smallest p-value to start with srsieve is p=44, so have to be greater than the base.
No, it just have to > all prime factors of gcd(k+-1,b-1), thus we can sieve start with p=5 (the gcd is 6, thus we should not sieve the primes 2 and 3), like the case of R36 (which can use the current srsieve, since 36 is even, the current srsieve can be used if and only if at least one of k and b is even), we can sieve R36 start with p=11, since we should not sieve the primes 5 and 7, it need not to be > 36
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