A122876 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

A122876

a(0)=1, a(1)=1, a(2)=2, a(n) = a(n-1) - a(n-2) for n>2.

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

COMMENTS

Essentially the same as A057079, A087204 and A100051.

LINKS

Table of n, a(n) for n=0..78.

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

FORMULA

a(n) = Sum_{k=0..floor(n/2)} (-2)^k*A055830(n-k,k).

G.f.: (1+2*x^2)/(1-x+x^2).

MATHEMATICA