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A168053 Expansion of (1-2*x^2-3*x^3)/((1-x)^2*(1+x+x^2)). 6
1, 1, -1, -3, -3, -5, -7, -7, -9, -11, -11, -13, -15, -15, -17, -19, -19, -21, -23, -23, -25, -27, -27, -29, -31, -31, -33, -35, -35, -37, -39, -39, -41, -43, -43, -45, -47, -47, -49, -51, -51, -53, -55, -55, -57, -59, -59, -61, -63, -63, -65, -67, -67, -69 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1).

FORMULA

a(n) = -(n^9 -45n^8 +846n^7 -8610n^6 +51345n^5 -181125n^4 +361584n^3 -361260n^2 +137264n -6720)/6720.

a(n) = A168054(n)/2^n.

MATHEMATICA

LinearRecurrence[{1, 0, 1, -1}, {1, 1, -1, -3}, 60] (* Harvey P. Dale, Jan 15 2015 *)

CoefficientList[Series[(1 - 2 x^2 - 3 x^3) / ((1 - x)^2 (1 + x + x^2)), {x, 0, 80}], x] (* Vincenzo Librandi, Jul 08 2016 *)

PROG

(MAGMA) m:=55; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1-2*x^2-3*x^3)/((1-x)^2*(1+x+x^2)))); // Bruno Berselli, May 31 2013

CROSSREFS

Cf. A168054.

Sequence in context: A070543 A342194 A196372 * A222657 A050826 A086910

Adjacent sequences:  A168050 A168051 A168052 * A168054 A168055 A168056

KEYWORD

sign,easy

AUTHOR

Paul Barry, Nov 17 2009

STATUS

approved

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Last modified April 11 11:31 EDT 2021. Contains 342886 sequences. (Running on oeis4.)