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-   -   This simple algorithm incomplete can only calculate prime numbers? (https://www.mersenneforum.org/showthread.php?t=20695)

ramshanker 2015-11-25 15:07

What is that [B]gp>[/B] console you guys using?

science_man_88 2015-11-25 15:12

[QUOTE=ramshanker;417237]What is that [B]gp>[/B] console you guys using?[/QUOTE]

[url]http://pari.math.u-bordeaux.fr/[/url]

Ale 2015-11-25 19:22

(20:15) gp > 304795270400000*3*4*5*6*3*2*4*5*7*8
%37 = 737360718151680000000
(20:16) gp > isprime(%-1)
%38 = 1
(20:17) gp >


thank you for the program PARI.
Now i can test , this is number 8 but .....

Ale 2015-11-25 19:46

(20:40) gp > 304795270400000*3*4*5*6*3*2*4*5*7*8*3*5*7*8*3*7*8*9
%67 = 936507100910085734400000000
(20:41) gp > isprime(%-1)
%68 = 1
(20:42) gp >

and this is the number 9 , but is different , is more complex , thinking

science_man_88 2015-11-25 19:56

[QUOTE=Ale;417263](20:40) gp > 304795270400000*3*4*5*6*3*2*4*5*7*8*3*5*7*8*3*7*8*9
%67 = 936507100910085734400000000
(20:41) gp > isprime(%-1)
%68 = 1
(20:42) gp >

and this is the number 9 , but is different , is more complex , thinking[/QUOTE]

still wondering what the "mechanism" is .

Ale 2015-11-25 20:01

chain of numbers, but I think it is impossible now

science_man_88 2015-11-25 20:04

[QUOTE=Ale;417266]chain of numbers, but I think it is impossible now[/QUOTE]

okay how is this chain produced ? and how can you guarantee it's prime ? edit: could the strong law of small numbers be playing a role ?

Ale 2015-11-25 20:23

the number * 3 *, is always after a series chain of numbers, example 2 * 4 * 5, but at 8 is not yet chain of numbers, see 2 * 4 * 5 * 7 * 8, there isn't 6.
I thought, example 2 * 4 * 5 repeated three times, 2 * 4 repeated two times , an so up .

science_man_88 2015-11-25 20:42

[QUOTE=Ale;417272]the number * 3 *, is always after a series chain of numbers, example 2 * 4 * 5, but at 8 is not yet chain of numbers, see 2 * 4 * 5 * 7 * 8, there isn't 6.
I thought, example 2 * 4 * 5 repeated three times, 2 * 4 repeated two times , an so up .[/QUOTE]

okay, so what are the specifics of the algorithm, and what is your level of knowledge of:
Va bene, quindi quali sono le specifiche dell'algoritmo, e qual è il vostro livello di conoscenza di:
1) Sieve techniques/tecniche di Sieve
2) remainder math/resto matematica
3) Prime numbers/numeri primi
4) Factorials/fattoriali
5) Programming/Programmazione

Ale 2015-11-25 20:57

only hobby

science_man_88 2015-11-25 21:15

[QUOTE=Ale;417277]only hobby[/QUOTE]

Okay well without specifics, it's pretty difficult to give a program equivalent to what needs to be done. do you know the fact that all primes greater than 3 must have a remainder of 1 or 5 when divided by 6 ? are you aware of how/why the sieve of Eratosthenes works ? are you aware of other ways to find prime numbers ?

Va bene anche senza specifiche, è piuttosto difficile dare un programma equivalente a quello che deve essere fatto. sapete il fatto che tutti i numeri primi superiore a 3 deve avere un resto di 1 o 5 quando diviso per 6? siete consapevoli di come / perché il crivello di Eratostene funziona? siete a conoscenza di altri modi per trovare i numeri primi?


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