A049071 Expansion of x*(3-2*x)/(1-x^2).

0, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3, -2, 3

Offset: 0

Author

N. J. A. Sloane

Keywords

• sign
• easy

Links

• B. R. Myers, On Spanning Trees, Weighted Compositions, Fibonacci Numbers, and Resistor Networks, SIAM Rev., 17 (1975), 465-474.
• Index entries for linear recurrences with constant coefficients, signature (0,1).

Programs

Mathematica

CoefficientList[Series[x (3-2x)/(1-x^2),{x,0,150}],x]  (* Harvey P. Dale, Mar 23 2011 *)

PARI

Vec(x*(3-2*x)/(1-x^2)+O(x^99)) \\ Charles R Greathouse IV, Sep 27 2012

Formula

a(n) = (1-5*(-1)^n)/2 for n>0. - Colin Barker, Jun 09 2015

a(n) = a(n-2) for n>2. - Colin Barker, Jun 09 2015