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User:Charles R Greathouse IV

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

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 September 25

A002064: Cullen numbers
Cn = n ⋅2n + 1, n ≥ 0
{ 1, 3, 9, 25, 65, 161, 385, 897, ... }
Grau proved that that there is no Cullen number with the Lehmer property. Hence, if
ϕ (Cn ) | (Cn − 1)
, then
is prime. A composite integer
is called a Lehmer number if
ϕ (m) | (m − 1)
, where
ϕ (m)
is the totient function.

Sequences in the News

  • September 15, 2016 Tom Greer's twin primes discovery is verified. These are currently the largest known twin primes.
  • September 14, 2016 Tom Greer discovers the twin primes 2996863034895 × 2 1290000 ± 1 using PrimeGrid, TwinGen and LLR.
  • January 19, 2016 Largest known term of A000043 announced: 274207281, also discovered by Curtis Cooper.
  • March 2, 2014 Fredrik Johansson announces a computation of the partition number \scriptstyle p(10^{20}) \approx 1.8381765\cdot10^{11140086259}, the largest known term of A000041.
  • December 6, 2013 Microsoft launches a challenge to find large non-Mersenne primes, A138837.
  • May 13, 2013 H. A. Helfgott submits a proof of the weak Goldbach conjecture, i.e. for odd numbers as sums of three primes: A007963 has no more zeroes.
  • January 25, 2013 Curtis Cooper discovers a new member of A000043, 57885161. Its index is not known but is at least 48.
  • January 13, 2013 The winners of the contest for new sequences in the OEIS at JMM 2013 were announced: A187824, A187771, and A187761.


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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