4
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0answers
42 views

Computing question: A quadratic which gives primes [on hold]

This is about Project Euler Problem 27. The question is: Considering quadratics of the form $n^2 + an + b$, where $\lvert a \rvert < 1000$ and $\lvert b \rvert < 1000$ Find the product ...
0
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1answer
61 views

How does this algorithm find the largest prime factor?

This question on math.stackexchange details an algorithm that can be used to find the largest prime factor of a number. I used it to solve Project Euler #3. Here's a short description of the ...
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vote
2answers
221 views

“Goldbach's other conjecture” and Project Euler - writing 1 as a sum of a prime and twice a square

From Problem 46 of Project Euler : It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square. $$9 = 7 + 2 \cdot ...
6
votes
3answers
9k views

Find the largest prime factor

I just "solved" the third Project Euler problem: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? With this on Mathematica: ...
3
votes
4answers
1k views

The longest sum of consecutive primes that add to a prime less than 1,000,000

In Project Euler problem $50,$ the goal is to find the longest sum of consecutive primes that add to a prime less than $1,000,000. $ I have an efficient algorithm to generate a set of primes ...
1
vote
1answer
433 views

Primality and repeated digits

I recently worked on problem 51 through project euler, I solved it essentially through brute-force but afterwards I viewed the forum and there were some more clever solutions. For those unfamiliar ...
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1answer
978 views

How to find large prime factors without using computer?

What is the largest prime factor of the number 600851475143 ? This is the third problem of Project Euler. How to approach this mathematically (without computer programming) ?
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votes
1answer
292 views

How to find the factors of numbers around 1e7?

I don't have a maths background but I'm solving problems on the awesome Project Euler .net in JavaScript as programming practice. I don't want to link directly to the question or post it verbatim ...