OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..500
Index entries for linear recurrences with constant coefficients, signature (1,2,1,-2,2,-2).
FORMULA
a(n) = a(n-1) + 2*a(n-2) + a(n-3) - 2*a(n-4) + 2*a(n-5) - 2*a(n-6) for n >= 6.
G.f.: (1 + x + 2*x^2 - 3*x^3 + 2*x^4 - 2*x^5)/(1 - x - 2*x^2 - x^3 + 2*x^4 - 2*x^5 + 2*x^6).
PROG
(PARI) Vec((1 + x + 2*x^2 - 3*x^3 + 2*x^4 - 2*x^5)/(1 - x - 2*x^2 - x^3 + 2*x^4 - 2*x^5 + 2*x^6) + O(x^40))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Andrew Howroyd, Feb 10 2020
STATUS
approved