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Search: Posts Made By: Dr Sardonicus
Forum: Charles Kusniec 2022-06-27, 02:46
Replies: 15
Views: 295
Posted By Dr Sardonicus
It would appear that you have a blog under your...

It would appear that you have a blog under your own name to serve as a repository for those of your posts/threads the Powers that Be deem to be unsuitable wherever else you may post them on the...
Forum: Miscellaneous Math 2022-06-27, 02:20
Replies: 28
Views: 583
Posted By Dr Sardonicus
If by "mod 17" you mean, "an element of the...

If by "mod 17" you mean, "an element of the residue ring of the integers Z mod 17Z," the terms "real" and "imaginary" are meaningless. I note that, mod 17, 4^2 +1 == 13^2 + 1 == 0 so 4 and 13 are...
Forum: Miscellaneous Math 2022-06-21, 18:58
Replies: 28
Views: 583
Posted By Dr Sardonicus
I believe the interpretation is correct. The key...

I believe the interpretation is correct. The key is that there is a defining polynomial. The required residues are the zeroes of x^2 - x - 1 (mod n). If n =p, a prime number, and p is congruent to...
Forum: FactorDB 2022-06-16, 18:59
Replies: 561
Views: 105,375
Posted By Dr Sardonicus
Unless your From: header was itself an invalid...

Unless your From: header was itself an invalid address.

A technique quite often used by spammers.[/QUOTE]That would make attributing not having gotten a response to the recipient's address not...
Forum: FactorDB 2022-06-15, 18:46
Replies: 561
Views: 105,375
Posted By Dr Sardonicus
I am doubt that it is really current, since I...

I am doubt that it is really current, since I have emailed him with this address, but he did not reply.[/QUOTE]It the address were not current, your email would have bounced.
Forum: storm5510 2022-06-14, 03:21
Replies: 29
Views: 649
Posted By Dr Sardonicus
Keeping a lawnmower in service for 30 years is...

Keeping a lawnmower in service for 30 years is commendable. The rule of thumb nowadays is that if you take care of your mower it will last 10 years. If you don't, it will last 5 years.

It is...
Forum: storm5510 2022-06-13, 20:12
Replies: 29
Views: 649
Posted By Dr Sardonicus
No. Burning a gallom of ethanol produces less...

No. Burning a gallom of ethanol produces less energy than burning a gallon of gasoline. Only about 2/3 the energy IIRC. So the more ethanol in the mixture, the lower your mileage will be.

The...
Forum: Soap Box 2022-06-12, 13:52
Replies: 37
Views: 1,142
Posted By Dr Sardonicus
The SF novelette The Little Black Bag by Cyril...

The SF novelette The Little Black Bag by Cyril Kornbluth (first published in the July 1950 Astounding Science Fiction, republished in, e.g. The Science Fiction Hall of Fame (Volume 1) is a...
Forum: storm5510 2022-06-12, 13:19
Replies: 29
Views: 649
Posted By Dr Sardonicus
One factor affecting the price of gas or diesel...

One factor affecting the price of gas or diesel is the price of crude oil. During the OPEC-Russia oil price war of 2020 (which was also during the COVID pandemic), Brent crude dropped below $20 per...
Forum: Homework Help 2022-06-10, 14:07
Replies: 24
Views: 1,129
Posted By Dr Sardonicus
I found this long-ago thread...

I found this long-ago thread (https://mersenneforum.org/showthread.php?t=20128) about this sort of thing...
Forum: Factoring 2022-06-10, 13:45
Replies: 61
Views: 4,321
Posted By Dr Sardonicus
If you look back a few posts in this thread,...

If you look back a few posts in this thread, you'll have your answer: they got moved to another thread.

If you want to see them, click on the link in this post...
Forum: Lounge 2022-06-10, 12:19
Replies: 379
Views: 46,987
Posted By Dr Sardonicus
June 10 (See this post...

June 10

(See this post (https://www.mersenneforum.org/showpost.php?p=598495&postcount=330) and the discussion which ensued in subsequent posts for more on the first two items.)

1942 Destruction...
Forum: Miscellaneous Math 2022-06-10, 11:55
Replies: 8
Views: 439
Posted By Dr Sardonicus
The following may be pertinent: Jon...

The following may be pertinent:

Jon Grantham, There are infinitely many Perrin pseudoprimes, J. Number Theory 130 (2010) 1117-1128

[$]\text{Theorem 1.1. Let }f (x)\;\in\;\mathbb{Z}[x]\text{ be...
Forum: Lounge 2022-06-09, 13:12
Replies: 379
Views: 46,987
Posted By Dr Sardonicus
June 9 68 AD Roman Emperor Nero (15 Dec 37 -...

June 9

68 AD Roman Emperor Nero (15 Dec 37 - 09 June 68), Lucius Domitius Ahenobarbus before becoming Emperor, then Nero Claudius Caesar Augustus Germanicus, "commits suicide" at age 30 after the...
Forum: Number Theory Discussion Group 2022-06-08, 16:10
Replies: 18
Views: 1,825
Posted By Dr Sardonicus
I was completely wrong about the criterion for g...

I was completely wrong about the criterion for g > 1 with g = gcd(d, f). I struck it out.

As an example, x^2 + y^2 == 3 (mod 15) is solvable (e.g. x = y = 3). I had failed to consider that x^2 +...
Forum: Other Mathematical Topics 2022-06-07, 23:49
Replies: 1
Views: 671
Posted By Dr Sardonicus
I agree, Quanta booted the title. A more...

I agree, Quanta booted the title. A more accurate title appears to be A proof of the Erdős primitive set conjecture (https://arxiv.org/abs/2202.02384) (Arxiv preprint).

I found a description of...
Forum: Lounge 2022-06-07, 12:33
Replies: 432
Views: 73,176
Posted By Dr Sardonicus
Then, I hung up and thought: "Are you even...

Then, I hung up and thought: "Are you even trying?"

I now wish I would have listened longer to see what other wisdom they had.[/QUOTE]Apparently they don't have to try very hard. The thought...
Forum: Lounge 2022-06-06, 13:01
Replies: 379
Views: 46,987
Posted By Dr Sardonicus
June 6 1939 The ship MS St. Louis, carrying...

June 6

1939 The ship MS St. Louis, carrying 907 Jewish refugees from Europe, begins sailing back to the continent after it was refused entry into America. Approximately a quarter of those on board...
Forum: Number Theory Discussion Group 2022-06-06, 12:38
Replies: 18
Views: 1,825
Posted By Dr Sardonicus
Let g = gcd(d, f).If g > 1 and any prime-power...

Let g = gcd(d, f).If g > 1 and any prime-power factor of g is congruent to 3 (mod 4) there is no solution.
If g = 1, f is divisible by 4 and d == 3 (mod 4) there is no solution.
If g = 1, f is...
Forum: Soap Box 2022-06-04, 12:40
Replies: 972
Views: 92,647
Posted By Dr Sardonicus
US Rep. Mo Brooks (R-AL) has another theory of...

US Rep. Mo Brooks (R-AL) has another theory of what causes mass shootings: Single mothers. And a "decline in moral values."

Given the fact that his party has become a personality cult, embracing...
Forum: Soap Box 2022-06-04, 03:34
Replies: 972
Views: 92,647
Posted By Dr Sardonicus
Like an R would be concerned with things like...

Like an R would be concerned with things like facts and truth. Such naivety, so cute...
Forum: Soap Box 2022-06-03, 12:03
Replies: 972
Views: 92,647
Posted By Dr Sardonicus
US Rep. Billy Long (R-MO) is blaming mass...

US Rep. Billy Long (R-MO) is blaming mass shootings on abortion. He says, “When I was growing up in Springfield, you had one or two murders a year. Now we have two, three, four a week in...
Forum: Lounge 2022-06-02, 12:48
Replies: 15
Views: 558
Posted By Dr Sardonicus
I have gotten rid of many unwanted woody plants...

I have gotten rid of many unwanted woody plants (small trees, etc) by cutting them down to short stumps, applying concentrated brush killer to the stump, and then covering the poisoned stump with a...
Forum: Soap Box 2022-06-02, 12:09
Replies: 972
Views: 92,647
Posted By Dr Sardonicus
5 people dead at Tulsa medical building, in the...

5 people dead at Tulsa medical building, in the 233rd mass shooting of 2022 (https://www.npr.org/2022/06/01/1102539255/multiple-people-shot-medical-building-tulsa-oklahoma)
Forum: Lounge 2022-06-02, 04:49
Replies: 42
Views: 3,547
Posted By Dr Sardonicus
In my experience, the yellow-orange Oleander...

In my experience, the yellow-orange Oleander Aphid (Aphis nerii) is the one that attacks Common Milkweed (Asclepias syriaca).

From Bugguide, Aphis nerii (https://bugguide.net/node/view/6167) -...
Showing results 1 to 25 of 1000

 
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