mersenneforum.org (https://www.mersenneforum.org/index.php)
-   MattcAnderson (https://www.mersenneforum.org/forumdisplay.php?f=146)
-   -   Matt A and the Online Encyclopedia of Integer Sequences (https://www.mersenneforum.org/showthread.php?t=20399)

 MattcAnderson 2015-08-04 04:08

Matt A and the Online Encyclopedia of Integer Sequences

Hi Math People,

The Online Encyclopedia of Integer Sequences is a good reference for integer information. Using a program written by Henry, I lengthened A257138, a list of 13 tuples. I found that the existing 18th entry had one digit too many. I informed the referees and am now waiting for a response. I have contributed to OEIS many times.

[URL]http://oeis.org/A257138[/URL]

Regards,
Matt

 ewmayer 2015-08-04 06:55

[QUOTE=MattcAnderson;407201]Hi Math People,

The Online Encyclopedia of Integer Sequences is a good reference for integer information. Using a program written by Henry, I lengthened A257138, a list of 13 tuples. I found that the existing 18th entry had one digit too many. I informed the referees and am now waiting for a response. I have contributed to OEIS many times.

[URL]http://oeis.org/A257138[/URL]

Regards,
Matt[/QUOTE]

Right - #18 should read 317294052871840123. Length anomaly is much more obvious when the sequence is displayed in list form.

 MattcAnderson 2015-08-10 01:01

The referees are working on this entry

 MattcAnderson 2015-08-13 20:24

Hi Math People,

You may see the draft entry for the OEIS entry I am working on now.

[url]https://oeis.org/draft/A257138[/url]

I am still waiting on the referees.

Regards,
Matt

 MattcAnderson 2015-08-17 15:14

Hi Math People,

A257138 has been corrected.

Regards,
Matt

 MattcAnderson 2016-09-10 05:47

A034856/

Hi Math People,

I was exploring oeis.org. This is the Online Encyclopedia of integer sequences.

[URL="oeis.org/A034856/"]oeis.org/A034856/[/URL]

Many people have double checked this encyclopedia.

I read that for A034856, a(n) reduces to n*(n+3)/2 - 1.

When I work it through, I reach the expression n*(n-1)/2 -1.

Probably I am wrong and the encyclopedia is right.

I assume that binomial(n,k) = n!/(k!(n-k)!).
Can someone else check this expression?

Regards,
Matt

 GP2 2016-09-10 07:25

[QUOTE=MattcAnderson;442116][URL="oeis.org/A034856/"]oeis.org/A034856/[/URL]

I read that for A034856, a(n) reduces to n*(n+3)/2 - 1.

When I work it through, I reach the expression n*(n-1)/2 -1.
[/QUOTE]

[CODE]
binomial(n+1, 2) + (n − 1)

n*(n+1) 2*(n−1)
= ------- + -------
2 2

n*n + 1*n + 2*n − 2
= -------------------
2

n*(n+3) − 2
= -----------
2

n*(n+3)
= ------- − 1
2
[/CODE]

 MattcAnderson 2016-09-10 14:20

Thank you GP2. You are correct.

Regards,
Matt

 MattcAnderson 2021-08-24 23:28

My contributions to OEIS

2 Attachment(s)
My best OEIS contribution is A201998. It was part of my "prime producing polynomial" project in 2006.

Matt

 MattcAnderson 2021-11-15 11:52

oeis.org slash A010882

Hi again all,

I thought that it would be fun to share about a OEIS (Online Encyclopedia of Integer Sequences) entry.
This one is a finite and repeating pattern.
Specifically, it starts with one and goes like one, two, three and again one, two, three.

look - [URL="oeis.org/A010882"]A010882[/URL]

Regards,
Matt

 Uncwilly 2021-11-16 14:52

My suggestion is, instead of making a new thread for each OEIS sequence that you find interesting, just have a single thread for all of them. I think it would be more interesting.

All times are UTC. The time now is 02:19.