OFFSET
0,3
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 (-2,3,4,-4).
FORMULA
From Colin Barker, Dec 04 2018: (Start)
a(n) = -2*a(n-1) + 3*a(n-2) + 4*a(n-3) - 4*a(n-4) for n>3.
a(n) = (16 + 11*(-2)^n + 3*(4+(-2)^n)*n) / 27.
(End)
MATHEMATICA
LinearRecurrence[{-2, 3, 4, -4}, {1, 0, 4, -4}, 100] (* Amiram Eldar, Dec 04 2018 *)
PROG
(PARI) Vec((1 + x)^2 / ((1 - x)^2*(1 + 2*x)^2) + O(x^40)) \\ Colin Barker, Dec 04 2018
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Dec 03 2018
STATUS
approved