A yuge number

enzocreti · 2018-12-05, 10:18

(2^7891456-1)*10^2375565+2^7891455-1

Is this number a probable prime or which is the smallest factor?

axn · 2018-12-05, 11:22

Quote:

Originally Posted by enzocreti

Is this number a probable prime

Almost certainly not.

Quote:

Originally Posted by enzocreti

or which is the smallest factor?

Could be too big for us to find out.

Why don't you do a PRP test using PFGW and find out if it is (probable) prime or composite?

axn · 2018-12-05, 13:23

No factors till 32*10^9. Quitting my attempt.

science_man_88 · 2018-12-05, 13:36

Quote:

Originally Posted by enzocreti

(2^7891456-1)*10^2375565+2^7891455-1

Is this number a probable prime or which is the smallest factor?

it won't have any factors in common with M3, M5,M11,M13, M283 , or M15413 to start. if it did then then the consecutive Mersenne numbers in question would have to share a factor. it also won't share factors with 2^15413+1 and a few other numbers. just using simple math.

enzocreti · 2018-12-06, 11:16

Quote:

Originally Posted by axn

No factors till 32*10^9. Quitting my attempt.

Can you tell me what program did you use?

axn · 2018-12-06, 13:29

Quote:

Originally Posted by enzocreti

Can you tell me what program did you use?

A quick 2-line throwaway script written in PARI/GP

enzocreti · 2018-12-06, 13:59

Quote:

Originally Posted by axn

A quick 2-line throwaway script written in PARI/GP

Can you give me the code?

Uncwilly · 2018-12-06, 14:42

Quote:

Originally Posted by enzocreti

Can you give me the code?

Go write it for yourself. Prove to us that you are willing to do some actual work in proving your number schemes. We have been spoonfeeding your.

axn · 2018-12-06, 15:45

Code:

mod_check(p)=my(r=Mod(2,p)^7891455); (r*2-1)*Mod(10,p)^2375565+r==1
forprime(p=2,,if(mod_check(p),print(p)))

Here you go...

enzocreti · 2018-12-06, 15:50

Quote:

Originally Posted by axn

Code:

mod_check(p)=my(r=Mod(2,p)^7891455); (r*2-1)*Mod(10,p)^2375565+r==1
forprime(p=2,,if(mod_check(p),print(p)))

Here you go...

ok thanks

Batalov · 2018-12-06, 15:56

Why not use Sage for that, though?

2018-12-05, 10:18	#1
enzocreti Mar 2018 1000010010₂ Posts	A yuge number (2^7891456-1)*10^2375565+2^7891455-1 Is this number a probable prime or which is the smallest factor?

2018-12-06, 15:45	#9
axn Jun 2003 2²×3×421 Posts	Code: mod_check(p)=my(r=Mod(2,p)^7891455); (r2-1)Mod(10,p)^2375565+r==1 forprime(p=2,,if(mod_check(p),print(p))) Here you go...

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2018-12-05, 13:23	#3
axn Jun 2003 2²·3·421 Posts	No factors till 32*10^9. Quitting my attempt.

2018-12-06, 15:56	#11
Batalov "Serge" Mar 2008 Phi(4,2^7658614+1)/2 3⁶·13 Posts	Why not use Sage for that, though?