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 A077953 Expansion of 1/(1-x+2*x^2-2*x^3). 8
 1, 1, -1, -1, 3, 3, -5, -5, 11, 11, -21, -21, 43, 43, -85, -85, 171, 171, -341, -341, 683, 683, -1365, -1365, 2731, 2731, -5461, -5461, 10923, 10923, -21845, -21845, 43691, 43691, -87381, -87381, 174763, 174763, -349525, -349525, 699051, 699051, -1398101, -1398101, 2796203, 2796203, -5592405 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Essentially the same as A077980. LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (1, -2, 2). FORMULA From Reinhard Zumkeller, Oct 07 2008: (Start) a(n+1) = a(n) - 2*a(n-1) + 2*a(n-2). a(n) = A077925(floor(n/2)-1) for n>1. (End) MAPLE seq(coeff(series(1/(1-x+2*x^2-2*x^3), x, n+1), x, n), n = 0 .. 40); # G. C. Greubel, Aug 07 2019 MATHEMATICA CoefficientList[Series[1/(1-x+2x^2-2x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[{1, -2, 2}, {1, 1, -1}, 50] (* Harvey P. Dale, Aug 27 2014 *) PROG (PARI) Vec(1/(1-x+2*x^2-2*x^3)+O(x^50)) \\ Charles R Greathouse IV, Sep 25 2012 (Magma) R:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1-x+2*x^2-2*x^3) )); // G. C. Greubel, Aug 07 2019 (Sage) (1/(1-x+2*x^2-2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Aug 07 2019 (GAP) a:=[1, 1, -1];; for n in [4..50] do a[n]:=a[n-1]-2*a[n-2]+2*a[n-3]; od; a; # G. C. Greubel, Aug 07 2019 CROSSREFS Cf. A077980. Cf. A007420, A077925. - Reinhard Zumkeller, Oct 07 2008 Sequence in context: A124115 A124114 A077893 * A077980 A286759 A146245 Adjacent sequences: A077950 A077951 A077952 * A077954 A077955 A077956 KEYWORD sign,easy AUTHOR N. J. A. Sloane, Nov 17 2002, Jun 17 2007 STATUS approved

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Last modified January 29 13:51 EST 2023. Contains 359923 sequences. (Running on oeis4.)