A122434 Expansion of (1+x)^3/(1+x+x^2).

1, 2, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0

Offset: 0

Author

Paul Barry, Sep 04 2006

Keywords

• easy
• sign

Comments

Row sums of number triangle A122433. Binomial transform is A077859.

Links

• Index entries for linear recurrences with constant coefficients, signature (-1,-1).

Programs

Mathematica

CoefficientList[Series[(1+x)^3/(1+x+x^2),{x,0,70}],x] (* or *) PadRight[ {1,2,0},71,{-1,1,0}] (* Harvey P. Dale, Apr 25 2012 *)

Formula

a(n) = 2*sqrt(3)*cos(2*Pi*n/3+Pi/6)/3+C(1,n)+C(0,n).

a(n) = -A049347(n) if n>=2 . - R. J. Mathar, Feb 08 2008