OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-1,0,0,1,1)
FORMULA
G.f.: (1-x+x^2+x^3)/((1+x)(1-x^4)).
a(n) = -a(n-1) + a(n-4) + a(n-5).
a(n) = -sin(pi*n/2+pi/4)/sqrt(2) + cos(pi*n+pi/4)/sqrt(2) + (-1)^n*(2n+3)/4 + 1/4.
MATHEMATICA
CoefficientList[Series[(1-x+x^2+x^3)/(1+x-x^4-x^5), {x, 0, 80}], x] (* or *) LinearRecurrence[{-1, 0, 0, 1, 1}, {1, -2, 3, -2, 3}, 80] (* Harvey P. Dale, Jul 14 2017 *)
PROG
(PARI) x='x+O('x^50); Vec((1-x+x^2+x^3)/(1+x-x^4-x^5)) \\ G. C. Greubel, Aug 29 2017
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Jul 24 2005
STATUS
approved