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Sequence of the Day
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A024816: Antisigma (n): , for .
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{ 0, 0, 2, 3, 9, 9, 20, 21, 32, 37, ... }
For primes , x̅σ ( p) = t p − 1 − 1 = − 1 |
, where is the -th triangular number.
Compare with Euler's cototient function .
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Featured article (Check back later for today's.)
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OEIS lookup
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<form action="http://oeis.org/search" method="get"><input type="submit" value="Search" name="go"><input maxLength="1024" size="55" dir="LTR" name="q" value="" title="Search Query"> <a href="http://oeis.org/hints.html">(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 http://www.mediawiki.org/wiki/Extension:InputBox) is under way...
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Did you know...
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On this day...
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- April 27, 1536 Rheticus earns his M.A. from Wittenberg.
- April 27, 1688 Abraham de Moivre is released from prison, according to some biographers. (After this date, he will travel to England).
- April 27, 1837 Paul Albert Gordan is born in Breslau (now Wrocław).
- April 27, 1884 Arthur Wieferich is born in Münster.
- April 27, 1887 Wilhelm Killing writes a letter to Friedrich Engel with the definition of a semi-simple Lie alebra with no abelian ideals.
- April 27, 1932 Gian-Carlo Rota is born in Vigevano.
- April 27, 1936 Karl Peason dies in Coldharbour, Surrey.
Sequences in the News
- Aug 17 2021 Swiss scientists announce they have calculated π (A000796) to 62.8 trillion digits in only 108 days.
- 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.
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