Thread: other conjectures View Single Post
 2020-07-20, 22:15 #20 kar_bon     Mar 2006 Germany 2·3·52·19 Posts 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. What I did: - looking the factorizations of the first values of (13*43^n-1)/6 - every n==0 mod 2 has factor 2 - every n==1 mod 3 has factor 3 - every n==3 mod 4 has factor 5 - every n==6 mod 8 has factor 17 - every n==1 mod 30 has factor 31 - every n==6 mod 22 has factor 23 Using awk with this: Code: BEGIN {print "44:M:1:43:258" >"t.txt" n=1 while (n < 1000000) { if (n % 2 == 0) {} # factor 2 else if (n % 3 == 1) {} # factor 3 else if (n % 4 == 3) {} # factor 5 else if (n % 8 == 6) {} # factor 17 else if (n % 30 == 1) {} # factor 31 else if (n % 22 == 6) {} # factor 23 else print "13 "n >>"t.txt" n++ } } creates "t.txt" like (in seconds) Code: 44:M:1:43:258 13 5 13 9 13 17 13 21 13 29 13 33 13 41 13 45 13 53 13 57 (...) for n<1M. Use sr1sieve on this to higher P. Changing the header after sieve to Code: ABC ($a*43^$b-1)/6 13 41 13 101 13 149 13 165 13 173 13 185 13 233 (..) and test it with PFGW. I got ~26,000 candiates left (don't know the exact P-value, was only a quick test).