A077930 Expansion of (1-x)^(-1)/(1+2*x+x^2+x^3).

1, -1, 2, -3, 6, -10, 18, -31, 55, -96, 169, -296, 520, -912, 1601, -2809, 4930, -8651, 15182, -26642, 46754, -82047, 143983, -252672, 443409, -778128, 1365520, -2396320, 4205249, -7379697, 12950466, -22726483, 39882198, -69988378, 122821042, -215535903, 378239143, -663763424

Offset: 0

Author

N. J. A. Sloane, Nov 17 2002

Keywords

• sign
• easy

Comments

Signed version of A060945: a(n) = (-1)^n * A060945(n).

Links

• Index entries for linear recurrences with constant coefficients, signature (-1,1,0,1).

Crossrefs

All of A060945, A077930, A181532 are variations of the same sequence. - N. J. A. Sloane, Mar 04 2012

Programs

Mathematica

CoefficientList[Series[1/(1-x)/(1+2x+x^2+x^3),{x,0,50}],x] (* or *) LinearRecurrence[ {-1,1,0,1},{1,-1,2,-3},50] (* Harvey P. Dale, Feb 20 2013 *)

PARI

Vec((1-x)^(-1)/(1+2*x+x^2+x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 24 2012

Formula

a(n+1)-a(n) = (-1)^(n+1)*A005314(n+2). - R. J. Mathar, Mar 14 2011

a(0)=1, a(1)=-1, a(2)=2, a(3)=-3, a(n)=-a(n-1)+a(n-2)+a(n-4). - Harvey P. Dale, Feb 20 2013