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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.

Projects:

Useful links:


Sequence of the Day

Sequence of the Day for September 26

A078437: Decimal expansion of sum of alternating series of reciprocals of primes

i   = 1
( − 1)i  − 1
1
pi
 .
0.26960635197167...

Here is another reminder of the infinitude of prime numbers. We may think we know a lot of prime numbers, but when it comes to computing this alternating series, this is the most precise we can get. The next digit is 4 or 5, we can’t say for sure just yet.

Today’s SOTD is about the sum of alternating series of reciprocals of primes, September 24’s SOTD was about the harmonic series of the primes (sum of the reciprocals of the primes).


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.


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).