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 paulunderwood 2021-09-15 11:19

[QUOTE=sweety439;587899][URL="https://primes.utm.edu/primes/status.php"]https://primes.utm.edu/primes/status.php[/URL]

id 132704 and 132705 are palindromes.[/QUOTE]

No they are not :no: Reversing the digits does not give the same number.

[url]https://primes.utm.edu/primes/page.php?id=132715[/url] is a palindrome. Congrats Serge and Ryan.

UTM's Prime Pages parser calculated the decimal digits as 1234568 :ermm:

 Batalov 2021-09-15 16:06

[QUOTE=paulunderwood;587905]UTM's Prime Pages parser calculated the decimal digits as 1234568 :ermm:[/QUOTE]
Prof.Caldwell's calculator had insufficient precision. I'll drop him a note. It is, of course, 1234567.

All palindromes of even length (except 11) are composite! :rolleyes:
[SPOILER]Hint: they are divisible by 11[/SPOILER]

 rudy235 2021-09-15 18:17

[QUOTE=paulunderwood;587879]I am looking forward to its revelation. The largest palindrome before this one had 490,001 digits. So 1,234,567 digits is quite amazing considering its crunching is done with generic modular reduction.[/QUOTE]

Wow! A megaprime palindrome. And one with more than twice the digits than the previous one!

I have to see it to believe it!:philmoore:

 Batalov 2021-09-15 21:52

When I was already way into sieving, I thought that I should have picked [C]1234321[/C] decimal digits length :rolleyes:

But it turned out good. With 1234567 digits' dataset the hit came, statistically speaking, [SPOILER]very![/SPOILER] early. So it [URL="https://primes.utm.edu/primes/page.php?id=132715"]was lucky[/URL].

 paulunderwood 2021-09-21 00:39

The prof has been busy. He fixed the palindrome length and puzzle-peter's arithmetic progression, which comes second on table two of [url]https://primes.utm.edu/top20/page.php?id=14[/url].

Hint: An AP9 could be quite easy to find to make it to the top of table two. For the AP8, I wrote my own GWNUM code which was 15% faster, I think mainly by dropping repetitive evaluations of the primorial coefficient. I'd willing to share it with any interested parties.

 Batalov 2021-09-21 01:30

Good! Excellent!
Even Kamada-san wrote to him and cc:'d me (as if I could help :rolleyes: ).

But it is fixed now, cool beans.

 pepi37 2021-09-22 10:07

[QUOTE=Batalov;587937]When I was already way into sieving, I thought that I should have picked [C]1234321[/C] decimal digits length :rolleyes:

But it turned out good. With 1234567 digits' dataset the hit came, statistically speaking, [SPOILER]very![/SPOILER] early. So it [URL="https://primes.utm.edu/primes/page.php?id=132715"]was lucky[/URL].[/QUOTE]

So if it is not secret how many candidates was tested before prime appear?

 ryanp 2021-09-22 12:51

[QUOTE=pepi37;588390]So if it is not secret how many candidates was tested before prime appear?[/QUOTE]

About 18,000 of the ~316K inputs that Serge originally sent me.

P.S. (S.B.) - the exact row number for the hit was 13,239th

 pepi37 2021-09-22 20:54

[QUOTE=ryanp;588395]About 18,000 of the ~316K inputs that Serge originally sent me.

P.S. (S.B.) - the exact row number for the hit was 13,239th[/QUOTE]

13239-th: small number of candidates for such prime. Very lucky hit :)

 rudy235 2021-09-25 01:14

This is an incredible result! [url]https://primes.utm.edu/primes/page.php?id=132738[/url]

But now we have [B][SIZE="4"]two[/SIZE][/B] different record arithmetic progression of 3 elements of 884,748 and 807,954 digits. the other one being. [URL="https://primes.utm.edu/primes/page.php?id=132738"]https://primes.utm.edu/primes/page.php?id=132738[/URL]

Still these AP-3 is truly impressive as the number of digits either is over 70% more than the previous one which was 406,437 digits.

Congratulations to Ryan and Serge.:bounce wave:

 paulunderwood 2021-09-27 20:59

Congrats to James Winskill for the mega primorial prime: [URL="https://primes.utm.edu/primes/page.php?id=132758"]3267113# - 1[/URL] (1,418,398 decimal digits).

:banana:

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