A078484 G.f.: -x*(1-2*x+2*x^2)/(2*x^3-4*x^2+4*x-1).
0, 1, 2, 6, 18, 52, 148, 420, 1192, 3384, 9608, 27280, 77456, 219920, 624416, 1772896, 5033760, 14292288, 40579904, 115217984, 327136896, 928835456, 2637230208, 7487852800, 21260161280, 60363694336, 171389837824, 486624896512, 1381667623424, 3922950583296
Offset: 0
Keywords
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- M. D. Atkinson and T. Stitt, Restricted permutations and the wreath product, Preprint, 2002.
- M. D. Atkinson and T. Stitt, Restricted permutations and the wreath product, Discrete Math., 259 (2002), 19-36.
- Index entries for linear recurrences with constant coefficients, signature (4, -4, 2).
Programs
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Mathematica
CoefficientList[Series[-x(1-2x+2x^2)/(2x^3-4x^2+4x-1),{x,0,30}],x] (* or *) Join[{0},LinearRecurrence[{4,-4,2},{1,2,6},30]] (* Harvey P. Dale, Jul 21 2012 *)
Formula
a(0)=0, a(1)=1, a(2)=2, a(3)=6, a(n) = 4*a(n-1)-4*a(n-2)+2*a(n-3). - Harvey P. Dale, Jul 21 2012
Extensions
Replaced definition with g.f. given by Atkinson and Stitt (2002). - N. J. A. Sloane, May 24 2016
Comments