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A077975
Expansion of 1/(1+x+x^2-2*x^3).
5
1, -1, 0, 3, -5, 2, 9, -21, 16, 23, -81, 90, 37, -289, 432, -69, -941, 1874, -1071, -2685, 7504, -6961, -5913, 27882, -35891, -3817, 95472, -163437, 60331, 294050, -681255, 507867, 761488, -2631865, 2886111, 1268730, -9418571, 13922063, -1966032, -30793173, 60603331, -33742222, -88447455
OFFSET
0,4
FORMULA
Recurrence: a(n) = 2a(n-3) - a(n-2) - a(n-1), starting 1,-1,0. - Ralf Stephan, Aug 18 2013
MATHEMATICA
CoefficientList[Series[1/(1+x+x^2-2x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[ {-1, -1, 2}, {1, -1, 0}, 50] (* Harvey P. Dale, Jul 20 2015 *)
PROG
(PARI) Vec(1/(1+x+x^2-2*x^3)+O(x^50)) \\ Charles R Greathouse IV, Sep 26 2012
(Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1+x+x^2-2*x^3) )); // G. C. Greubel, Jun 25 2019
(Sage) (1/(1+x+x^2-2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 25 2019
(GAP) a:=[1, -1, 0];; for n in [4..50] do a[n]:=-a[n-1]-a[n-2]+2*a[n-3]; od; a; # G. C. Greubel, Jun 25 2019
CROSSREFS
Sequence in context: A101157 A193725 A077952 * A356378 A258656 A112323
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved