A105812 Expansion of (1+x-x^2)/(1+x).

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

Offset

0,1

Comments

Row sums of number triangle A105810.

Links

Table of n, a(n) for n=0..77.

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

Formula

a(n) = -(-1)^n-binomial(1, n)+3*binomial(0, n).

a(n) = A033999(n-1), n>1. - R. J. Mathar, Aug 28 2008

E.g.f.: 2 - x - exp(-x). - Alejandro J. Becerra Jr., Feb 17 2021

Mathematica

LinearRecurrence[{-1}, {1, 0, -1}, 78] (* Ray Chandler, Jul 30 2015 *)

Prog

(PARI) a(n)=if(n<2, 1-n, -(-1)^n) \\ Charles R Greathouse IV, Jun 06 2013

Crossrefs

Cf. A033999, A105810.

Sequence in context: A079054 A131695 A324113 * A134323 A060576 A261012

Adjacent sequences: A105809 A105810 A105811 * A105813 A105814 A105815

Keyword

easy,sign

Author

Paul Barry, May 04 2005

Status

approved