The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A047220

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A047220

Numbers that are congruent to {0, 1, 3} mod 5.
(history; published version)

#64 by Andrew Howroyd at Thu Aug 15 10:58:06 EDT 2024

STATUS

reviewed

approved

#63 by Michel Marcus at Thu Aug 15 10:41:28 EDT 2024

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proposed

reviewed

#62 by Pontus von Brömssen at Thu Aug 15 10:35:17 EDT 2024

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editing

proposed

#61 by Pontus von Brömssen at Thu Aug 15 10:33:52 EDT 2024

COMMENTS

Maximum sum of degeneracies over all decompositions of the complete graph of order n into four factors. The extremal decompositions are characterized in the Bickle link below. - Allan Bickle, Dec 21 2021

LINKS

Z. Furedi, Füredi, A. Kostochka, M. Stiebitz, R. Skrekovski, and D. West, <a href="https://faculty.math.illinois.edu/~west/pubs/norgad.pdf">Nordhaus-Gaddum-type theorems for decompositions into many parts</a>, J. Graph Theory 50 (2005), 273-292.

STATUS

approved

editing

#60 by Michel Marcus at Sun Apr 16 03:17:25 EDT 2023

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reviewed

approved

#59 by Joerg Arndt at Sun Apr 16 02:18:32 EDT 2023

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proposed

reviewed

#58 by Amiram Eldar at Sun Apr 16 02:08:35 EDT 2023

STATUS

editing

proposed

#57 by Amiram Eldar at Sun Apr 16 01:59:00 EDT 2023

FORMULA

Sum_{n>=2} (-1)^n/a(n) = sqrt(1-2/sqrt(5))*Pi/5 + 2*log(phi)/sqrt(5) + log(2)/5, where phi is the golden ratio (A001622). - Amiram Eldar, Apr 16 2023

CROSSREFS

Cf. A001622, A011655, A130196 (first differences).

STATUS

approved

editing

#56 by Charles R Greathouse IV at Thu Sep 08 08:44:56 EDT 2022

PROG

(MAGMAMagma) I:=[0, 1, 3, 5]; [n le 4 select I[n] else Self(n-1)+Self(n-3)-Self(n-4): n in [1..70]]; // Vincenzo Librandi, Apr 26 2012

Discussion

Thu Sep 08

08:44

OEIS Server: https://oeis.org/edit/global/2944

#55 by N. J. A. Sloane at Wed Dec 22 14:25:04 EST 2021

STATUS

proposed

approved