Forum: YAFU
2020-02-15, 14:55
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Replies: 485
Views: 57,029
Don't think this one's turned up before:
...
Don't think this one's turned up before:
02/15/20 06:53:28 v1.35-beta @ BLACKBOX2,
02/15/20 06:53:28 v1.35-beta @ BLACKBOX2, ****************************
02/15/20 06:53:28 v1.35-beta @...
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Forum: Miscellaneous Math
2019-10-23, 14:29
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Replies: 50
Views: 4,521
Consider the equation 3d+4e = 6d+2e.
This is...
Consider the equation 3d+4e = 6d+2e.
This is true for the specific values d = 2 and e = 3, for example. This does not allow us to conclude that 3 = 6 and 4 = 2.
(Also from what I can tell the...
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Forum: Miscellaneous Math
2019-04-06, 19:32
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Replies: 15
Views: 1,184
There are lots of very smart people on...
There are lots of very smart people on stackexchange but they don't like being given long messy expressions like yours, with no explanation of how they were derived, and asked to simplify them. Most...
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Forum: Miscellaneous Math
2019-04-06, 16:57
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Replies: 15
Views: 1,184
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Forum: Miscellaneous Math
2019-02-04, 23:40
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Replies: 40
Views: 2,580
Bringing back an argument I've used before.
...
Bringing back an argument I've used before.
Proof that there are infinitely many primes of the form n2-1:
Suppose there are finitely many primes of this form. Then there must be a prime that...
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Forum: Conjectures 'R Us
2019-01-07, 10:59
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Replies: 132
Views: 32,553
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Forum: Conjectures 'R Us
2018-12-31, 18:11
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Replies: 132
Views: 32,553
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Forum: And now for something completely different
2018-04-13, 11:09
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Replies: 11
Views: 5,138
But this doesn't affect the finiteness or...
But this doesn't affect the finiteness or otherwise of the sequence, as Cunningham chains are finite. Also, as the terms get larger, the probability of hitting a Cunningham chain
should tend to 0...
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Forum: And now for something completely different
2018-04-12, 08:45
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Replies: 11
Views: 5,138
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Forum: Aliquot Sequences
2018-04-03, 12:25
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Replies: 6
Views: 5,285
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Forum: Aliquot Sequences
2018-04-03, 00:12
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Replies: 6
Views: 5,285
Yes: oeis.org/A146556
Seems not -...
Yes: oeis.org/A146556
Seems not - actually g(3) = 30, and g(4) = 492. The only OEIS match for these terms is oeis.org/A143414 which is clearly unrelated.
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Forum: FactorDB
2018-04-02, 13:23
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Replies: 21
Views: 9,633
The thing is, they do.
It appears that you...
The thing is, they do.
It appears that you are computing the aliquot sequence of 2^(p-1)*(2^p-1)*3 for some Mersenne prime 2^p-1. If a has no common factors with 2^(p-1)*(2^p-1), then...
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Forum: Miscellaneous Math
2018-03-06, 18:08
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Replies: 21
Views: 2,801
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Forum: Miscellaneous Math
2018-03-03, 14:07
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Replies: 53
Views: 4,121
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Forum: Miscellaneous Math
2018-03-02, 20:38
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Replies: 53
Views: 4,121
I fully understand this, and I never said you...
I fully understand this, and I never said you believed it. What you're doing is a proof by contradiction, where you assume that something is true (in this case, that there is a prime that "ends all...
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Forum: Miscellaneous Math
2018-03-02, 19:55
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Replies: 53
Views: 4,121
Here's a proof that there are infinitely many...
Here's a proof that there are infinitely many primes of the form n2-1:
Suppose there are finitely many primes of the form n2-1.
Then there is some prime p which "ends the possibilities" of...
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Forum: Miscellaneous Math
2018-03-02, 19:44
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Replies: 21
Views: 2,801
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Forum: Conjectures 'R Us
2018-01-25, 20:02
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Replies: 132
Views: 32,553
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Forum: gophne
2018-01-07, 09:24
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Replies: 272
Views: 31,794
I don't think you've taken on board what axn...
I don't think you've taken on board what axn meant by this:
The point is that, if n is odd, then gcd(n, n+2N) = gcd(n, N) and so you are just checking if n has any common factors with N. But...
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Forum: gophne
2018-01-06, 10:39
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Replies: 272
Views: 31,794
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Forum: gophne
2018-01-05, 23:17
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Replies: 272
Views: 31,794
Gophne, as actual proofs don't seem to have...
Gophne, as actual proofs don't seem to have persuaded you, let's have a look at an example to see that the two tests are the same. I'm going to avoid modular arithmetic as much as possible because it...
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Forum: Prime Gap Searches
2018-01-01, 14:11
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Replies: 233
Views: 42,177
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Forum: gophne
2017-12-31, 23:58
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Replies: 29
Views: 7,015
Here is some Pari code to run your test for...
Here is some Pari code to run your test for numbers n+2 from 1 to 10000, and print the false positives along with a counter:
x=0;for(n=-1,9998,if(isprime(n+2)==0&&(2^n-1)%(n+2)==(n+1)/2,x++;print(x"...
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Forum: gophne
2017-12-31, 19:25
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Replies: 272
Views: 31,794
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Forum: Miscellaneous Math
2017-12-29, 22:36
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Replies: 69
Views: 4,379
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