This site is supported by donations to The OEIS Foundation.

Main Page/Prototype

From OeisWiki
Jump to: navigation, search
Welcome to the OEIS wiki,
the wiki complement to the On-Line Encyclopedia of Integer Sequences.
179,247 articles.

OEIS Reader's Guide

Contributor's Guide

Editor's Guide

Selected Recent Additions

  • A239797 Decimal expansion of .
  • A238271 Decimal expansion of .
  • A237042 UPC check digits.
  • A236603 Lowest canonical Gray cycles of length .
  • A235365 Smallest odd prime factor of .
  • A234522 Decimal expansion of .
  • A233748 Number of graphs on n vertices with edges colored with at most four interchangeable colors under the symmetries of the full edge permutation group.
  • A232499 Number of unit squares, aligned with a Cartesian grid, completely within the first quadrant of a circle centered at the origin ordered by increasing radius.
  • A231963 Concatenate with its UPC check digit.
  • A230624 Numbers with property that for every base , there is a number such that , where is the sum of digits in the base expansion of .

Sequence of the Day

Sequence of the Day for October 19

A065918: Logarithm of
2 +
2  3
This number figures in the search for Mersenne primes thus: the Mersenne number
M = 2n  −  1
is prime if and only if

cosh (2n  − 2 log (2 +
2  3
e  + { 2n  − 2 log (2 +
2  3
 ) }
+ e  − { 2n  − 2 log (2 +
2  3
 ) }
(2 +
2  3
 )  + { 2n  − 2  } + (2 +
2  3
 )  − { 2n  − 2  }

cosh (x)
is the hyperbolic cosine function. David Wilson has proposed calling the number
log (2 +
2  3
the Helms constant.
The number
2 +
2  3
= tan
5 π
= cot
is sometimes called the Kasner constant (see A019973 for decimal expansion).

Featured article (Check back later for today's.)

OEIS lookup

<form action="" method="get"><input type="submit" value="Search" name="go"><input maxLength="1024" size="55" dir="LTR" name="q" value="" title="Search Query"> <a href="">(hints)</a></form>

(This is a trial template:OEIS lookup -- as you can see, it does not work. Request for a convenient wiki extension (such as is under way...

Did you know...

On this day...

  • October 19, 1675 John Collins writes a letter to James Gregory about John Wallis calculating some lengths on an impossible triangle.
  • October 19, 1903 Jean Frédéric Auguste Delsarte born in Fournies.

Sequences in the News

  • Dec 25 2018 German Heise-News "integers, please" column explains A003173 and OEIS.
  • 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.

Featured picture (Check back later for today's.)

Related web sites

In case you would not find here what you are looking for (after a thorough search), you might want to visit some related web sites:

The On-Line Encyclopedia of Integer Sequences™ (OEIS™) Wiki

This is the Wiki part of the OEIS, at
Here you will find discussion pages related to the OEIS — everything except the sequences themselves.

The main OEIS page is at
Use that page for looking up a sequence, searching the OEIS database, contributing new sequences, editing sequences, etc.
NOTE: Looking up a sequence or an A-number should be done at the main OEIS, not in the search boxes on this page!

The OEIS is owned, maintained and supported by The OEIS Foundation Inc. — please donate!

The On-Line Encyclopedia of Integer Sequences™ (OEIS™) Wiki

These are links to the OEIS Wiki

Welcome to OEIS (needs to be reformatted for wiki)


Register (so that you can submit sequences or suggest changes)

Trouble registering, logging in, changing password

Editorial Board

Registered Users

Q and A

Questions and Answers Page For New OEIS

Questions and Answers Page for OEIS License Agreements


Style Sheet for OEIS (under construction)

Instructions For General Users

Instructions For Associate Editors

Instructions For Editors-in-Chief


Index to OEIS

Index to fractions in OEIS

Other links

Deleted Sequences

Complaints About Editing

More Pages

Works Citing OEIS

The Multi-faceted Reach of the OEIS

The On-Line Encyclopedia of Integer Sequences™ (OEIS™)

These are links to the main OEIS

Recent additions to OEIS

Sequences awaiting review (drafts proposed for review)

Sequences being edited (drafts not proposed for review)