OFFSET
0,4
COMMENTS
Connected with tiling of torus by squares (see A322038).
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-2,-1,4,4,0,-4).
FORMULA
a(n) = -2*a(n-1) - a(n-2) + 4*a(n-3) + 4*a(n-4) - 4*a(n-6) for n>5. - Colin Barker, Dec 04 2018
MATHEMATICA
LinearRecurrence[{-2, -1, 4, 4, 0, -4}, {1, 0, 0, 4, -4, 4}, 100] (* Amiram Eldar, Dec 04 2018 *)
CoefficientList[Series[(1+x)^2/((1-x)^2(1+2x+2x^2)^2), {x, 0, 40}], x] (* Harvey P. Dale, Jan 20 2021 *)
PROG
(PARI) Vec((1 + x)^2 / ((1 - x)^2*(1 + 2*x + 2*x^2)^2) + O(x^40)) \\ Colin Barker, Dec 04 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Dec 03 2018
STATUS
approved