mersenneforum.org 1+1 selfridges test for 1/8 of numbers
 Register FAQ Search Today's Posts Mark Forums Read

 2021-11-16, 23:54 #1 paulunderwood     Sep 2002 Database er0rr 22·1,063 Posts 1+1 selfridges test for 1/8 of numbers I was playing around while I waiting for some results to come in... For n=3 mod 4 such that kronecker(-3,n)==-1 and kronecker(-7,n)==-1 test Mod(2,n)^((n-1)/2)==kronecker(2,n) and Mod(-7,n)^((n-1)/2)==-1. That's it! It is 1+1 selfridges. I have tested it for n < 7*10^9 so far. Pretty good, eh? Can you fool it? For convenience here is the test: Code: {tst(n)=n%4==3&&kronecker(-3,n)==-1&&kronecker(-7,n)==-1&& Mod(-7,n)^((n-1)/2)==-1&&Mod(2,n)^((n-1)/2)==kronecker(2,n);} Morning after... A quick 1 second scan of Jan Feitsma's 2-PSP list yields the fraud tst(619033*670619). Last fiddled with by paulunderwood on 2021-11-17 at 08:13

 Similar Threads Thread Thread Starter Forum Replies Last Post paulunderwood Miscellaneous Math 2 2021-10-14 22:03 bhelmes Miscellaneous Math 0 2021-06-07 00:43 bhelmes Miscellaneous Math 35 2021-04-10 17:01 paulunderwood Miscellaneous Math 21 2020-11-20 13:16 sweety439 sweety439 7 2020-02-11 19:49

All times are UTC. The time now is 19:22.

Wed Aug 17 19:22:05 UTC 2022 up 41 days, 14:09, 1 user, load averages: 2.13, 1.62, 1.50