OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4,-2,0,-11,0,-2,4,-1).
FORMULA
G.f.: ((1-x-x^2)^2 + 4*x^2 - 4*x^4) / ((1-x-x^2)^2 - 4*x^3)^2.
a(n) = 4*a(n-1) - 2*a(n-2) - 11*a(n-4) - 2*a(n-6) + 4*a(n-7) - a(n-8).
MATHEMATICA
CoefficientList[Series[((1-x-x^2)^2+4*x^2-4*x^4)/((1-x-x^2)^2-4*x^3)^2, {x, 0, 50}], x] (* Vincenzo Librandi, Jan 01 2026 *)
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(((1-x-x^2)^2+4*x^2-4*x^4)/((1-x-x^2)^2-4*x^3)^2)
(Magma) m:=50; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1-x-x^2)^2 + 4*x^2 - 4*x^4) / ((1-x-x^2)^2 - 4*x^3)^2); // Vincenzo Librandi, Jan 01 2026
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 22 2025
STATUS
approved
