The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A239571

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A239571

Number of ways to place 5 points on a triangular grid of side n so that no two of them are adjacent.
(history; published version)

#25 by Charles R Greathouse IV at Thu Sep 08 08:46:07 EDT 2022

PROG

(MAGMAMagma) [(n^2-7*n+12)*(n^8+12*n^7-58*n^6-860*n^5+2141*n^4 +23728*n^3-61316*n^2-244928*n+770880)/3840: n in [3..40]]; // Vincenzo Librandi, Mar 23 2014

Discussion

Thu Sep 08

08:46

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

#24 by Joerg Arndt at Wed Mar 08 11:56:30 EST 2017

STATUS

editing

approved

#23 by Heinrich Ludwig at Wed Mar 08 11:54:09 EST 2017

COMMENTS

Rotations and reflections of placements are counted. If they are to be ignored see A239575.

CROSSREFS

Cf. A239567, A239575, A239568 (2 points), A239569 (3 points), A239570 (4 points), A282998 (6 points).

STATUS

approved

editing

Discussion

Wed Mar 08

11:54

Heinrich Ludwig: Comment and 2 crossrefs added.

#22 by Ray Chandler at Tue Jul 14 10:46:11 EDT 2015

STATUS

editing

approved

#21 by Ray Chandler at Tue Jul 14 10:46:06 EDT 2015

LINKS

<a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (11,-55,165,-330,462,-462,330,-165,55,-11,1)

STATUS

approved

editing

#20 by Charles R Greathouse IV at Sat Jun 13 00:54:59 EDT 2015

LINKS

<a href="/index/Rec#order_11">Index to sequences with entries for linear recurrences with constant coefficients</a>, signature (11,-55,165,-330,462,-462,330,-165,55-11,1)

Discussion

Sat Jun 13

00:54

OEIS Server: https://oeis.org/edit/global/2439

#19 by Bruno Berselli at Mon Mar 24 04:09:32 EDT 2014

STATUS

proposed

approved

#18 by Joerg Arndt at Sun Mar 23 08:39:43 EDT 2014

STATUS

editing

proposed

#17 by Joerg Arndt at Sun Mar 23 08:39:35 EDT 2014

FORMULA

a(n) = (n -3) * (n -4) * (n^8 +12*n^7 -58*n^6 -860*n^5 +2141*n^4 + 23728*n^3 -61316*n^2 -244928*n +770880)/3840.

STATUS

proposed

editing

#16 by Vincenzo Librandi at Sun Mar 23 05:08:31 EDT 2014

STATUS

editing

proposed