OFFSET
0,2
COMMENTS
Hankel transform of A187306.
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..9999
Paul Barry, On a Central Transform of Integer Sequences, arXiv:2004.04577 [math.CO], 2020.
Index entries for linear recurrences with constant coefficients, signature (2,-3,2,-1)
FORMULA
G.f.: (1+x^2-x^3)/(1-x+x^2)^2.
a(n) = (1/3)*(2*n+2-(n-1)*cos(2*n*Pi/3)-(n-1)*cos(4*n*Pi/3)-cos((2*n+1)*Pi/3)-sin((8*n+1)*Pi/6))*(-1)^floor(n/3). - Wesley Ivan Hurt, Sep 25 2017
MATHEMATICA
LinearRecurrence[{2, -3, 2, -1}, {1, 2, 2, -1}, 120] (* Harvey P. Dale, Jan 21 2019 *)
PROG
(PARI) Vec((1+x^2-x^3)/(1-x+x^2)^2 + O(x^80)) \\ Michel Marcus, Sep 26 2017
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Barry, Mar 08 2011
STATUS
approved