OFFSET
1,3
LINKS
FORMULA
From Philippe Deléham, Dec 05 2008 [corrected by Sergei N. Gladkovskii, Dec 10 2012]: (Start)
a(n) = -A124302(n-1).
G.f.: -(1-3*x+x^2)/(1-4*x+3*x^2). (End)
G.f.: -1-x*G(0) where G(k) = 1 + 2*x/(1 - 2*x - x*(1-2*x)/(x + (1-2*x)*2/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Dec 10 2012
MAPLE
a[1]:=-1: a[2]:=-1: a[3]:=-2: for n from 4 to 29 do a[n]:=4*a[n-1]-3*a[n-2] od: seq(a[n], n=1..29);
MATHEMATICA
M = {{1, -1, 0}, {-1, 2, -1}, {0, -1, 1}} v[1] = {1, 0, 0} v[n_] := v[n] = M.v[n - 1] a1 = Table[ -v[n][[1]], {n, 1, 50}]
CROSSREFS
KEYWORD
sign,easy,less
AUTHOR
Roger L. Bagula, Oct 02 2006
EXTENSIONS
Edited by N. J. A. Sloane, Oct 08 2006
STATUS
approved