OFFSET
2,1
LINKS
Iain Fox, Table of n, a(n) for n = 2..10000
Index entries for linear recurrences with constant coefficients, signature (3,-6,7,-6,3,-1).
FORMULA
G.f.: -x^2*(3-8x^2+6x^3-3x^4+x^5)/(1-x+x^2)^3.
From Iain Fox, Feb 26 2018: (Start)
a(n) = 3*a(n-1) - 6*a(n-2) + 7*a(n-3) - 6*a(n-4) + 3*a(n-5) - a(n-6).
a(3*k+1) = (-1)^k, where k is an integer >= 1.
(End)
MATHEMATICA
CoefficientList[Series[ -(3-8x^2+6x^3-3x^4+x^5)/(1-x+x^2)^3, {x, 0, 70}], x]
PROG
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Mario Catalani (mario.catalani(AT)unito.it), Feb 14 2003
EXTENSIONS
G.f. corrected by Iain Fox, Feb 26 2018
STATUS
approved