The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A242073 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A242073

a(n) = - (a(n-1)*a(n-4) + a(n-2)*a(n-3)) / a(n-5) with a(0)=1, a(1)=a(2)=-1, a(3)=-2, a(4)=1.
(history; published version)

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

PROG

(MAGMAMagma) I:=[1, -1, -1, -2, 1, -1]; [n le 6 select I[n] else -Self(n-6): n in [1..100]]; // Vincenzo Librandi, Jul 22 2015

Discussion

Thu Sep 08

08:46

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

#23 by Joerg Arndt at Thu Aug 31 08:21:06 EDT 2017

STATUS

proposed

approved

#22 by Antti Karttunen at Thu Aug 31 05:21:13 EDT 2017

STATUS

editing

proposed

#21 by Antti Karttunen at Thu Aug 31 05:20:33 EDT 2017

LINKS

Antti Karttunen, <a href="/A242073/b242073.txt">Table of n, a(n) for n = 0..11999</a>

STATUS

approved

editing

#20 by Charles R Greathouse IV at Sun Aug 16 12:04:00 EDT 2015

LINKS

<a href="/index/Rec#order_06">Index to sequences with entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,-1).

Discussion

Sun Aug 16

12:04

OEIS Server: https://oeis.org/edit/global/2451

#19 by N. J. A. Sloane at Sun Aug 02 17:57:05 EDT 2015

STATUS

proposed

approved

#18 by Vincenzo Librandi at Wed Jul 22 02:07:33 EDT 2015

STATUS

editing

proposed

#17 by Vincenzo Librandi at Wed Jul 22 02:07:25 EDT 2015

MATHEMATICA

LinearRecurrence[{0, 0, 0, 0, 0, -1}, {1, -1, -1, -2, 1, -1}, 100] (* Vincenzo Librandi, Jul 22 2015 *)

PROG

(MAGMA) I:=[1, -1, -1, -2, 1, -1]; [n le 6 select I[n] else -Self(n-6): n in [1..100]]; // Vincenzo Librandi, Jul 22 2015

STATUS

proposed

editing

#16 by Wesley Ivan Hurt at Tue Jul 21 23:47:22 EDT 2015

STATUS

editing

proposed

#15 by Wesley Ivan Hurt at Tue Jul 21 23:45:39 EDT 2015

LINKS

<a href="/index/Rec#order_06">Index to sequences with linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,-1).

FORMULA

a(n) = ((-1)^(n/2)+(-1)^(3*n/2)+(-1)^((3+n)/6)-(-1)^((3-n)/6)+(-1)^((3-7*n)/6)-(-1)^((3+7*n)/6))/2. - Wesley Ivan Hurt, Jul 21 2015

MAPLE

A242073:=proc(n) option remember;

if n=0 then 1 elif n=1 then -1 elif n=2 then -1 elif n=3 then -2 elif n=4 then 1 elif n=5 then -1 else -A242073(n-6); fi; end: seq(A242073(n), n=0..100); # Wesley Ivan Hurt, Jul 21 2015

CROSSREFS

Cf. A057079.

KEYWORD

sign,easy

STATUS

approved

editing