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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:



[talk]

Sequence of the Day for June 29

A090684: Primes of the form
8n 2 − 1
.
{ 7, 31, 71, 127, 199, 647, 967, 1151, 1567, 2311, 2591, 2887, 3527, 4231, ... }
221 223 225 227 229 231 233 235 237 239 241
219 145 147 149 151 153 155 157 159 161 163
217 143 85 87 89 91 93 95 97 99 165
215 141 83 41 43 45 47 49 51 101 167
213 139 81 39 13 15 17 19 53 103 169
211 137 79 37 11 1 3 21 55 105 171
209 135 77 35 9 7 5 23 57 107 173
207 133 75 33 31 29 27 25 59 109 175
205 131 73 71 69 67 65 63 61 111 177
203 129 127 125 123 121 119 117 115 113 179
201 199 197 195 193 191 189 187 185 183 181

In the odd number variant of the Ulam spiral, unimpeded by the even numbers, the prime numbers can line up in horizontal and vertical lines. But there are still noticeable diagonal lines of primes, and these primes fall on one such diagonal.


Sequences in the News

  • November 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.
  • 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.


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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