OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1000
H. S. M. Coxeter, Loxodromic sequences of tangent spheres, Aequationes Mathematicae, 1.1-2 (1968): 104-121. See p. 112.
Index entries for linear recurrences with constant coefficients, signature (2,2,2,-1)
FORMULA
G.f.: (-1 + 4*x + x^2 - 2*x^3)/(1 - 2*x - 2*x^2 - 2*x^3 + x^4). - Andrew Howroyd, Sep 08 2018
MATHEMATICA
LinearRecurrence[{2, 2, 2, -1}, {-1, 2, 3, 6}, 30] (* Jean-François Alcover, Sep 13 2018 *)
PROG
(PARI) Vec((-1 + 4*x + x^2 - 2*x^3)/(1 - 2*x - 2*x^2 - 2*x^3 + x^4) + O(x^40)) \\ Andrew Howroyd, Sep 08 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Sep 03 2018
EXTENSIONS
Terms a(8) and beyond from Andrew Howroyd, Sep 08 2018
STATUS
approved