A020868 Number of single component edge-subgraphs in Moebius ladder M_n.

60, 397, 2464, 14809, 87000, 502261, 2859968, 16105801, 89879304, 497792981, 2739398160, 14992582713, 81664018712, 442972209365, 2394012778496, 12896089147849, 69266060508360, 371057114908533, 1983022462947472, 10574870140601337, 56281372512713240

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 (15,-85,239,-391,405,-275,121,-32,4).

Formula

G.f.: see G in the Maple program. - Emeric Deutsch, Dec 21 2004

Maple

G := (28*x^8-220*x^7+841*x^6-1943*x^5+2882*x^4-2746*x^3+1609*x^2-503*x+60)*x^2/(x^2-2*x+1)/(-1+6*x-5*x^2+2*x^3)^2/(1-x): Gser:=series(G, x=0, 25): seq(coeff(Gser, x^n), n=2..23); # Emeric Deutsch, Dec 21 2004

Prog

(PARI) Vec(-x^2*(28*x^8 -220*x^7 +841*x^6 -1943*x^5 +2882*x^4 -2746*x^3 +1609*x^2 -503*x +60) / ((x -1)^3*(2*x^3 -5*x^2 +6*x -1)^2) + O(x^30)) \\ Colin Barker, Aug 01 2015

Crossrefs

Sequence in context: A060489 A088942 A135037 * A223461 A088943 A097387

Adjacent sequences: A020865 A020866 A020867 * A020869 A020870 A020871

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Emeric Deutsch, Dec 21 2004

Status

approved