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A020869 Number of single component forests in Moebius ladder M_n. 1
34, 222, 1280, 6955, 36378, 185178, 923696, 4535991, 22000490, 105640634, 503067648, 2379006071, 11183747330, 52306745310, 243553038816, 1129612848795, 5221079904978, 24057393297286, 110543216068160, 506673892786803, 2317069421129034, 10574292843014802 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Colin Barker, Table of n, a(n) for n = 2..1000

J. P. McSorley, Counting structures in the Moebius ladder, Discrete Math., 184 (1998), 137-164.

Index entries for linear recurrences with constant coefficients, signature (13,-64,156,-218,190,-108,40,-9,1).

FORMULA

G.f.=x^2*(3x^8-27x^7+126x^6-360x^5+663x^4-781x^3+570x^2-220x+34)/[(1-x)^3*(1-5x+3x^2-x^3)^2]. - Emeric Deutsch, Dec 21 2004

The McSorley reference gives the approximation a(n)~.8757*n*4.3652^n-1.5432*n*.4786^n*cos(.8458*n+.9674)+n^2-2*n. - Emeric Deutsch, Dec 21 2004

MAPLE

G:=x^2*(3*x^8-27*x^7+126*x^6-360*x^5+663*x^4-781*x^3+570*x^2-220*x+34)/(1-x)^3/(1-5*x+3*x^2-x^3)^2: Gser:=series(G, x=0, 27): seq(coeff(Gser, x^n), n=2..25); # - Emeric Deutsch, Dec 21 2004

PROG

(PARI) Vec(-x^2*(3*x^8-27*x^7+126*x^6-360*x^5+663*x^4-781*x^3+570*x^2-220*x+34) / ((x-1)^3*(x^3-3*x^2+5*x-1)^2) + O(x^30)) \\ Colin Barker, Aug 01 2015

CROSSREFS

Sequence in context: A302227 A058581 A050263 * A055716 A233300 A281052

Adjacent sequences:  A020866 A020867 A020868 * A020870 A020871 A020872

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Emeric Deutsch, Dec 21 2004

STATUS

approved

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Last modified January 20 21:36 EST 2019. Contains 319336 sequences. (Running on oeis4.)