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User:Charles R Greathouse IV

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Editor-in-Chief, interested primarily in computational number theory and allied fields.

I can be contacted via my Talk page here, or by email.

User:Charles R Greathouse IV/Averages Early draft of an article.
User:Charles R Greathouse IV/Chase sequences 'Chase sequences': Axxxxxx refers to Ayyyyyy, which refers to Azzzzzz...
User:Charles R Greathouse IV/Favorites Some of my favorite sequences.
User:Charles R Greathouse IV/Format Discusses the correct format of b-files and how to repair ill-formatted b-files.
User:Charles R Greathouse IV/Junk Disreputable publishers, journals, etc.
User:Charles R Greathouse IV/Keywords Information on keywords: when to use them, new ones to add, etc.
User:Charles R Greathouse IV/Metadata Plans for OEIS metadata: keywords, categories, the index, etc.
User:Charles R Greathouse IV/Pari Some PARI/GP tools.
User:Charles R Greathouse IV/Programs Programs in the OEIS: types, format, etc.
User:Charles R Greathouse IV/Projects Other mathematical databases, fingerprint databases, and similar projects
User:Charles R Greathouse IV/Properties Sequence properties and classes
User:Charles R Greathouse IV/Rule of thumb Sequences should take 1 hour to prepare for submission.
User:Charles R Greathouse IV/Standards How to write up certain kinds of sequences.
User:Charles R Greathouse IV/Tables of special primes Types of primes and their densities
User:Charles R Greathouse IV/To do Sequences to work on and b-files to fix.
User:Charles R Greathouse IV/Vanity Sequences named after their discoverer.
User:Charles R Greathouse IV/Wiki Tools for the OEIS wiki.

Projects:

Useful links:


Sequence of the Day

Sequence of the Day for November 26

A000055: Number of trees with
n, n   ≥   0,
 unlabeled nodes.
{ 1, 1, 1, 1, 2, 3, 6, 11, 23, 47, 106, 235, ... }

Trees with
n
 unlabeled nodes[1]

n
 		Trees
0
Null tree
1 
●
2 
●—●
3 
●—●—●
4 
             ●
            /
●—●—●—●  ●—●  
            \
             ●
5 
                 ●    ●
                /     |
●—●—●—●—●  ●—●—●    ●—●—●  
                \     |
                 ●    ●

This is the sequence for the example search on the front page of the OEIS. This Thanksgiving we are thankful for, among other things, the OEIS, which is an invaluable resource in many mathematical and scientific endeavors.

__________

  1. ↑ Weisstein, Eric W., Tree, from MathWorld—A Wolfram Web Resource.


Sequences in the News

  • Aug 17 2021 Swiss scientists announce they have calculated π (A000796) to 62.8 trillion digits in only 108 days.
  • Dec 25 2018 German Heise-News "integers, please" column explains A003173 and OEIS.
  • Feb 01 2018 Alphabet announced a $8,589,869,056 = $A000396(6) stock buyback.
  • Jan 03 2018 Largest known term of A000043 announced: 77232917.
  • Nov 18 2016 PrimeGrid proves that 10223 is not a Sierpinski number, since 10223 × 2 31172165 + 1 is prime. So no changes to A076336 for now.
  • Sep 14 2016 Tom Greer discovers the twin primes 2996863034895 × 2 1290000 ± 1 using PrimeGrid, TwinGen and LLR.
  • Jan 19 2016 Largest known term of A000043 announced: 74207281, also discovered by Curtis Cooper.


Complaints

I strive to live up to the highest ethical standards. If you feel that I have wrongly rejected one of your sequences (or otherwise failed to meet the expected standards), please leave a note at Complaints About Editing where it will be reviewed. I hope that in all cases you will first contact me (through the pink comment boxes, on my user page, or by email).

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