The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A090860

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A090860

Number of ways of 4-coloring a map in which there is a central circle surrounded by an annulus divided into n-1 regions. There are n regions in all.
(history; published version)

#36 by Peter Luschny at Tue Apr 09 14:21:00 EDT 2024

STATUS

reviewed

approved

#35 by Amiram Eldar at Tue Apr 09 12:58:43 EDT 2024

STATUS

proposed

reviewed

#34 by Amiram Eldar at Tue Apr 09 12:58:40 EDT 2024

STATUS

editing

proposed

#33 by Amiram Eldar at Tue Apr 09 12:58:34 EDT 2024

LINKS

S. B. Step, <a href="http://hp.vector.co.jp/authors/VA008683/english/index.htm">More information</a>.

STATUS

proposed

editing

#32 by Stefano Spezia at Tue Apr 09 11:39:32 EDT 2024

STATUS

editing

proposed

#31 by Stefano Spezia at Tue Apr 09 11:39:29 EDT 2024

FORMULA

m=4, a(n)=m*((m-2)^(n-1)+(-1)^(n-1)*(m-2)); recurrence m=4, b(1)=0, b(2)=(m-1)*(m-2), b(n)=(m-2)*b(n-2)+(m-3)*b(n-1), a(n)=m*b(n-1).

CROSSREFS

Cf. A001045, A092297.

STATUS

proposed

editing

#30 by Michel Marcus at Tue Apr 09 11:26:15 EDT 2024

STATUS

editing

proposed

#29 by Michel Marcus at Tue Apr 09 11:26:12 EDT 2024

LINKS

<a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,2).

STATUS

approved

editing

#28 by Charles R Greathouse IV at Thu Sep 08 08:45:12 EDT 2022

PROG

(MAGMAMagma) [2^(n+1)-8*(-1)^n: n in [4..35]]; // Vincenzo Librandi, Oct 10 2011

Discussion

Thu Sep 08

08:45

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

#27 by Harvey P. Dale at Sat Jan 25 17:16:34 EST 2020

STATUS

editing

approved