OFFSET
0,4
REFERENCES
Murat Sahin and Elif Tan, Conditional (strong) divisibility sequences, Fib. Q., 56 (No. 1, 2018), 18-31.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,9,0,-12)
FORMULA
G.f.: -x*(3*x^2-x-1)/(12*x^4-9*x^2+1). - Alois P. Heinz, Mar 10 2018
a(n) = 9*a(n-2) - 12*a(n-4) for n>3. - Colin Barker, Mar 11 2018
MAPLE
a:= n-> (<<0|1>, <-12|9>>^iquo(n, 2, 'r'). <<r, 5*r+1>>)[1, 1]:
seq(a(n), n=0..35); # Alois P. Heinz, Mar 10 2018
MATHEMATICA
Fold[Append[#1, Inner[Times, Boole[OddQ@ #2] + {1, 3}, {#1[[-1]], #1[[-2]]}, Plus]] &, {0, 1}, Range[2, 30]] (* or *)
CoefficientList[Series[-x (3 x^2 - x - 1)/(12 x^4 - 9 x^2 + 1), {x, 0, 30}], x] (* Michael De Vlieger, Mar 10 2018 *)
PROG
(PARI) concat(0, Vec(x*(1 + x - 3*x^2) / (1 - 9*x^2 + 12*x^4) + O(x^30))) \\ Colin Barker, Mar 11 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 10 2018
EXTENSIONS
More terms from Altug Alkan, Mar 10 2018
STATUS
approved