OFFSET
0,4
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-1,-2,2).
FORMULA
a(n) = (-1)^n * A077956(n). - G. C. Greubel, Jun 25 2019
MATHEMATICA
LinearRecurrence[{-1, -2, 2}, {1, -1, -1}, 50] (* Vincenzo Librandi, Sep 09 2016 *)
PROG
(Magma) I:=[1, -1, -1]; [n le 3 select I[n] else -Self(n-1)-2*Self(n-2)+2*Self(n-3): n in [1..50]]; // Vincenzo Librandi, Sep 09 2016
(PARI) Vec(1/(1+x+2*x^2-2*x^3) + O(x^50)) \\ Michel Marcus, Sep 09 2016
(Sage) (1/(1+x+2*x^2-2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 25 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, Jun 25 2019
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved