mersenneforum.org Code for testing a prime other than form 2^n-1
 User Name Remember Me? Password
 Register FAQ Search Today's Posts Mark Forums Read

 2013-04-18, 05:34 #1 MercPrime     Jan 2009 1/n 3×7 Posts Code for testing a prime other than form 2^n-1 Hello, I thought there was a guide to entering a line in the worktodo file, but I searched and cant seem to find it. I have a candidate for a Sophia Prime of form 2^n +1 or there abouts (small number, nothing huge) and was looking to do a quick test. So is there a way to specify the form, or would I have to crunch the numbers to come up with an exponent that has decimals or something. Thanks!
 2013-04-18, 11:59 #2 TimSorbet Account Deleted     "Tim Sorbera" Aug 2006 San Antonio, TX USA 11·389 Posts http://www.mersenneforum.org/showpos...33&postcount=6 shows the worktodo line formats. If you're trying to do something that's not supported by Prime95, check out PFGW or LLR. Last fiddled with by TimSorbet on 2013-04-18 at 12:00
2013-04-18, 17:37   #3
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

19·232 Posts

Quote:
 Originally Posted by MercPrime ...I have a candidate for a Sophia Prime of form 2^n +1 ...
All 2^n+1 numbers (except n=2m) are composite, in case you were unsure.

 2013-04-19, 03:20 #4 MercPrime     Jan 2009 1/n 1516 Posts Thank you Mini-Geek and Batalov, been a while so I have to dust off the brain a little!
 2013-05-12, 18:35 #5 Unregistered   2·3·113 Posts Mersenne Primes The point of the program is that there is a special method to find primes which CAN be expressed as (2^P)-1. There are definitely some prime numbers expressed as (2^P)+1 (I think for certain even P's...) but those numbers cannot use the Lucas Lehmer algorithm. The algorithm was specially designed for Mersenne primes only. It saves an enormous amount of time over other conventional primality tests which is why all the biggest primes discovered to date are Mersenne primes. I couldn't explain the proof of the Lucas Lehmer test if I tried, but I do know it takes advantage of the fact that the binary form of a mersenne number is 111.........111, whereas your proposed candidate is 1000.........0001.
2013-05-12, 22:03   #6

"Richard B. Woods"
Aug 2002
Wisconsin USA

170148 Posts

Quote:
 Originally Posted by Unregistered There are definitely some prime numbers expressed as (2^P)+1 (I think for certain even P's...)
... but, as pointed out above, only if P = 2m.

 Similar Threads Thread Thread Starter Forum Replies Last Post JeppeSN Math 117 2022-08-30 16:41 carpetpool Miscellaneous Math 6 2017-09-01 13:59 a1call Information & Answers 17 2017-02-26 22:01 PawnProver44 Miscellaneous Math 9 2016-03-19 22:11 arbooker And now for something completely different 14 2015-05-22 23:18

All times are UTC. The time now is 01:09.

Sat Jan 28 01:09:06 UTC 2023 up 162 days, 22:37, 0 users, load averages: 1.15, 1.10, 1.05

Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.

≠ ± ∓ ÷ × · − √ ‰ ⊗ ⊕ ⊖ ⊘ ⊙ ≤ ≥ ≦ ≧ ≨ ≩ ≺ ≻ ≼ ≽ ⊏ ⊐ ⊑ ⊒ ² ³ °
∠ ∟ ° ≅ ~ ‖ ⟂ ⫛
≡ ≜ ≈ ∝ ∞ ≪ ≫ ⌊⌋ ⌈⌉ ∘ ∏ ∐ ∑ ∧ ∨ ∩ ∪ ⨀ ⊕ ⊗ 𝖕 𝖖 𝖗 ⊲ ⊳
∅ ∖ ∁ ↦ ↣ ∩ ∪ ⊆ ⊂ ⊄ ⊊ ⊇ ⊃ ⊅ ⊋ ⊖ ∈ ∉ ∋ ∌ ℕ ℤ ℚ ℝ ℂ ℵ ℶ ℷ ℸ 𝓟
¬ ∨ ∧ ⊕ → ← ⇒ ⇐ ⇔ ∀ ∃ ∄ ∴ ∵ ⊤ ⊥ ⊢ ⊨ ⫤ ⊣ … ⋯ ⋮ ⋰ ⋱
∫ ∬ ∭ ∮ ∯ ∰ ∇ ∆ δ ∂ ℱ ℒ ℓ
𝛢𝛼 𝛣𝛽 𝛤𝛾 𝛥𝛿 𝛦𝜀𝜖 𝛧𝜁 𝛨𝜂 𝛩𝜃𝜗 𝛪𝜄 𝛫𝜅 𝛬𝜆 𝛭𝜇 𝛮𝜈 𝛯𝜉 𝛰𝜊 𝛱𝜋 𝛲𝜌 𝛴𝜎𝜍 𝛵𝜏 𝛶𝜐 𝛷𝜙𝜑 𝛸𝜒 𝛹𝜓 𝛺𝜔