The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A227327

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A227327

Number of non-equivalent ways to choose two points in an equilateral triangle grid of side n.
(history; published version)

#33 by Joerg Arndt at Sun Nov 03 04:54:15 EST 2024

STATUS

proposed

approved

#32 by Jason Yuen at Sun Nov 03 04:50:46 EST 2024

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editing

proposed

#31 by Jason Yuen at Sun Nov 03 04:50:43 EST 2024

COMMENTS

The sequence is an alternating composition of A178073 and A071244: a(n) = 2*A071244((n+1)/2) if n is odd, otherwise a(n) = A178073(n/2)).

STATUS

approved

editing

#30 by Alois P. Heinz at Thu Mar 03 13:07:49 EST 2022

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proposed

approved

#29 by Michel Marcus at Thu Mar 03 12:41:01 EST 2022

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editing

proposed

#28 by Michel Marcus at Thu Mar 03 12:40:57 EST 2022

LINKS

<a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (3,-1,-5,5,1,-3,1).

STATUS

approved

editing

#27 by Harvey P. Dale at Sat May 11 09:24:24 EDT 2019

STATUS

editing

approved

#26 by Harvey P. Dale at Sat May 11 09:24:20 EDT 2019

MATHEMATICA

LinearRecurrence[{3, -1, -5, 5, 1, -3, 1}, {0, 1, 4, 10, 22, 41, 72}, 50] (* Harvey P. Dale, May 11 2019 *)

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approved

editing

#25 by N. J. A. Sloane at Tue Nov 08 22:18:01 EST 2016

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proposed

approved

#24 by Jon E. Schoenfield at Tue Nov 08 18:00:33 EST 2016

STATUS

editing

proposed