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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/Projects Other mathematical databases, fingerprint databases, and similar projects
User:Charles R Greathouse IV/Tables of special primes Types of primes and their densities
User:Charles R Greathouse IV/Rule of thumb Sequences should take 1 hour to prepare for submission.
User:Charles R Greathouse IV/Chase sequences 'Chase sequences': Axxxxxx refers to Ayyyyyy, which refers to Azzzzzz...
User:Charles R Greathouse IV/Programs Programs in the OEIS: types, format, etc.
User:Charles R Greathouse IV/Properties Sequence properties and classes
User:Charles R Greathouse IV/Metadata Plans for OEIS metadata: keywords, categories, the index, etc.
User:Charles R Greathouse IV/Favorites Some of my favorite sequences.
User:Charles R Greathouse IV/Keywords Information on keywords: when to use them, new ones to add, etc.
User:Charles R Greathouse IV/To do Sequences to work on and b-files to fix.
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/Pari Some Pari tools.
User:Charles R Greathouse IV/Wiki Tools for the OEIS wiki.


Useful links:


Sequence of the Day for July 26

A034872: Central column of Lozanić's triangle.

{ 1, 1, 1, 2, 4, 6, 10, 19, 38, 66, 126, 236, 472, 868, ... }

Note that although the values of odd-numbered columns are only listed once, they appear twice in the triangle.

Lozanić's triangle
Row sums
ni  = 0T (n, i)
= 0
1 1
1 1 1 2
2 1 1 1 3
3 1 2 2 1 6
4 1 2 4 2 1 10
5 1 3 6 6 3 1 20
6 1 3 9 10 9 3 1 36
7 1 4 12 19 19 12 4 1 72

Sequences in the News

  • January 19, 2016 Largest known term of A000043 announced: 274207281, also discovered by Curtis Cooper.
  • March 2, 2014 Fredrik Johansson announces he's computed p(1020), which he says is approximately 1.8381765 × 10 11140086259. Once confirmed and verified, it will be 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.
  • September 21, 2012 Nick Berry, founder of Data Genetics, finds that the 17th most common 10-digit ATM PIN is 3141592654 (see A011546).


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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