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User:Charles R Greathouse IV

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Vice President of the OEIS and Editor-in-Chief, interested primarily in computational number theory and allied fields.

I can be contacted via my Talk page here, or by email: my first name (charles) at my initials (crg4) dot com. Other email addresses may work as well.

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/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.


Useful links:

Sequence of the Day for August 17

A014549: Gauß’s constant
2  1  −  x 4
d  x
This is the reciprocal of the arithmetic-geometric mean of 1 and
2  2 
. It was on May 30, 1799 that Carl Friedrich Gauß discovered the integral for this number shown above.

Its simple continued fraction is (see A053002)

M  (1,
2  2 
1 + 
5 + 
21 + 
3 + 
4 + 
14 + 

Sequences in the News

  • 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.
  • Mar 02 2014 Fredrik Johansson announces a computation of the partition number p(10 20) ≈ 1.8381765 × 10 11140086259, the largest known term of A000041.
  • Dec 06 2013 Microsoft launches a challenge to find large non-Mersenne primes, A138837.


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).