OFFSET
1,3
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,6,-2,-4).
FORMULA
a(n) = a(n-1) + 6*a(n-2) - 2*a(n-3) - 4*a(n-4) for n > 4.
G.f.: x*(1 + 2*x^2) / ((1 - x)*(1 + 2*x)*(1 - 2*x - 2*x^2)). - Colin Barker, Jun 07 2018
MATHEMATICA
LinearRecurrence[{1, 6, -2, -4}, {1, 1, 9, 13}, 30] (* Harvey P. Dale, Jun 02 2019 *)
PROG
(PARI) Vec(x*(1 + 2*x^2) / ((1 - x)*(1 + 2*x)*(1 - 2*x - 2*x^2)) + O(x^40)) \\ Colin Barker, Jun 07 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jun 07 2018
STATUS
approved