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A052904 Expansion of (1-x)/(1-2x-4x^2+4x^3). 1
1, 1, 6, 12, 44, 112, 352, 976, 2912, 8320, 24384, 70400, 205056, 594176, 1726976, 5010432, 14552064, 42237952, 122642432, 356028416, 1033674752, 3000893440, 8712372224, 25293619200, 73433153536, 213191294976, 618940727296 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..26.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 882

Index entries for linear recurrences with constant coefficients, signature (2,4,-4).

FORMULA

G.f.: -(-1+x)/(1-2*x-4*x^2+4*x^3)

Recurrence: {a(1)=1, a(0)=1, a(2)=6, 4*a(n)-4*a(n+1)-2*a(n+2)+a(n+3)=0}

Sum(-1/37*(-4-14*_alpha+13*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-4*_Z^2+4*_Z^3))

MAPLE

spec := [S, {S=Sequence(Prod(Z, Union(Sequence(Z), Z, Z, Z, Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);

MATHEMATICA

CoefficientList[Series[(1-x)/(1-2x-4x^2+4x^3), {x, 0, 30}], x] (* or *) LinearRecurrence[{2, 4, -4}, {1, 1, 6}, 30] (* Harvey P. Dale, Jan 17 2013 *)

CROSSREFS

Sequence in context: A034529 A121160 A105863 * A106692 A032470 A018809

Adjacent sequences:  A052901 A052902 A052903 * A052905 A052906 A052907

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from James A. Sellers, Jun 08 2000

STATUS

approved

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Last modified August 20 05:25 EDT 2019. Contains 326139 sequences. (Running on oeis4.)