Search found 32 matches

by S_r
Sun Dec 24, 2017 9:09 am
Forum: Number
Topic: Prime generation
Replies: 3
Views: 9491

Prime generation

If you add 2,4,6..... To these four prime numbers then you will get a series of primes 5- 5,7,11,17,25 11-11,13,17,23,31,41,53,67,83,101,121 17- 17,19,23,29,37,47,59,73,89,107,127,149,173,199,227,257,289 41- 41,43,47,53,61,71,83,97,113,131,151,173,197,223,251,281,313,347,383,421,461,503,547,593,641,...
by S_r
Fri Sep 15, 2017 5:47 pm
Forum: Recreational
Topic: How to factor
Replies: 8
Views: 8592

Re: How to factor

As i have learnt sieving has limits. What if i want to factor a 20 digit number or say a 50 digit number. How would I do it?
by S_r
Tue Sep 12, 2017 3:42 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 609
Replies: 10
Views: 4736

Re: Problem 609

Thank you very much
by S_r
Mon Sep 11, 2017 6:18 pm
Forum: Clarifications on Project Euler Problems
Topic: Problem 609
Replies: 10
Views: 4736

Re: Problem 609

You mean if n=4 then following pi sequences can be created
4,2,1 and 4,2 and only one of them have one not prime, k=c(u), which is 4,2.
Is it? Correct me if I'm wrong.

If that's correct help me with last doubt. Who will choose values of n and k?
by S_r
Mon Sep 11, 2017 8:18 am
Forum: Clarifications on Project Euler Problems
Topic: Problem 609
Replies: 10
Views: 4736

Problem 609

I didn't understand the following line :-
Let p(n,k) be the number of π sequences u for which $u_0$ ≤n and c(u)=k .

can you please clear it to me with a suitable example?
by S_r
Mon Sep 11, 2017 8:02 am
Forum: Recreational
Topic: How to factor
Replies: 8
Views: 8592

Re: How to factor

euler wrote: Sun Sep 10, 2017 11:51 am @S_r: Are you requiring a list of all the divisors or do you need to know the number of divisors / sum of divisors?
Hi,
I want to know how to get all the prime factors of a number.
Recently I have learnt sieving from Muthu, which is an excellent method. still looking for more efficient methods.
by S_r
Sat Sep 09, 2017 4:20 pm
Forum: Recreational
Topic: How to factor
Replies: 8
Views: 8592

Re: How to factor

To be specific the problem requires all the factors and not only the prime ones so-
1 how would it help by taking the sqrt(n)
2 all factors are needed(not only the primes)
3 i dont know how to use sieve

And finally in india the power supply has never run for a day continuously
by S_r
Sat Sep 09, 2017 9:07 am
Forum: Recreational
Topic: How to factor
Replies: 8
Views: 8592

How to factor

The only method of factoring that i know is trial division. When i used it in solving a problem i got to know how bad it is. As the number increases the number of factors increses too. Even after calculating for two hours the number reached was not even one fourth of destined number. Help me please....
by S_r
Fri Sep 08, 2017 12:12 pm
Forum: Recreational
Topic: Suggest me a book
Replies: 14
Views: 15130

Re: Suggest me a book

Anything on number theory? Which branch do you like?
by S_r
Fri Sep 08, 2017 12:11 pm
Forum: Recreational
Topic: Suggest me a book
Replies: 14
Views: 15130

Re: Suggest me a book

Thanks
by S_r
Thu Sep 07, 2017 9:49 am
Forum: Recreational
Topic: Suggest me a book
Replies: 14
Views: 15130

Suggest me a book

Which books would you prefer if i want to learn about number theory, factoring, different methods of finding primes and a great book on maths?
by S_r
Thu Sep 07, 2017 9:44 am
Forum: Recreational
Topic: hello from indonesia
Replies: 1
Views: 6317

Re: hello from indonesia

Good for you. Which language do you use?