The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A001909 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A001909

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

#52 by Michel Marcus at Tue Jul 30 01:53:09 EDT 2024

STATUS

reviewed

approved

#51 by Joerg Arndt at Tue Jul 30 01:42:53 EDT 2024

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proposed

reviewed

#50 by Jason Yuen at Mon Jul 29 21:47:11 EDT 2024

STATUS

editing

proposed

#49 by Jason Yuen at Mon Jul 29 21:47:06 EDT 2024

FORMULA

a(n) = hypergeom([5,-n+3],[],1))*(-1)^(n+1) for n>=3. - Peter Luschny, Sep 20 2014

STATUS

approved

editing

#48 by Harvey P. Dale at Tue Jul 17 13:54:42 EDT 2018

STATUS

editing

approved

#47 by Harvey P. Dale at Tue Jul 17 13:54:38 EDT 2018

MATHEMATICA

nxt[{n_, a_, b_}]:={n+1, b, b(n+1)+a(n-3)}; NestList[nxt, {3, 0, 1}, 20][[All, 2]] (* Harvey P. Dale, Jul 17 2018 *)

STATUS

approved

editing

#46 by Wesley Ivan Hurt at Fri Feb 06 14:11:19 EST 2015

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reviewed

approved

#45 by Tom Edgar at Fri Feb 06 12:18:40 EST 2015

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proposed

reviewed

#44 by Michel Marcus at Fri Feb 06 12:17:53 EST 2015

STATUS

editing

proposed

#43 by Michel Marcus at Fri Feb 06 12:17:42 EST 2015

REFERENCES

Roland Bacher, Counting Packings of Generic Subsets in Finite Groups, Electr. J. Combinatorics, 19 (2012), #P7. - From N. J. A. Sloane, Feb 06 2013

Seok-Zun Song et al., Extremes of permanents of (0,1)-matrices, Lin. Algebra and its Applic. 373 (2003), p. 197-210.

LINKS

Roland Bacher, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v19i3p7">Counting Packings of Generic Subsets in Finite Groups</a>, Electr. J. Combinatorics, 19 (2012), #P7. - From N. J. A. Sloane, Feb 06 2013

Seok-Zun Song et al., <a href="http://dx.doi.org/10.1016/S0024-3795(03)00382-3">Extremes of permanents of (0,1)-matrices</a>, Special issue on the Combinatorial Matrix Theory Conference (Pohang, 2002). Linear Algebra Appl. 373 (2003), pp. 197-210.

FORMULA

G.f.: x*hypergeom([1,5],[],x/(x+1))/(x+1). - _Mark van Hoeij, _, Nov 07 2011

CROSSREFS

Cf. A000255, A000153, A000261, A001910, A090010, A055790, A090012-A090016, A086764. A000261 (necklaces and three cords).

A000261 (necklaces and three cords).

STATUS

proposed

editing