OFFSET
1,2
COMMENTS
Number of orthogonal arrays OA(4,n,2,1).
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..150
J.-Z. Zhang, Z.-S. You and Z.-L. Li, Enumeration of binary orthogonal arrays of strength 1, Discrete Math., 239 (2000), 191-198.
Index entries for linear recurrences with constant coefficients, signature (8,-12).
FORMULA
From Colin Barker, Oct 20 2015: (Start)
a(n) = 8*a(n-1)-12*a(n-2).
G.f.: 24*x^2 / ((2*x-1)*(6*x-1)). (End)
MATHEMATICA
Table[2^n(3^n-3), {n, 30}] (* or *) LinearRecurrence[{8, -12}, {0, 24}, 30] (* Harvey P. Dale, Jul 28 2019 *)
PROG
(PARI) { for (n=1, 150, write("b066406.txt", n, " ", 2^n*(3^n - 3)) ) } \\ Harry J. Smith, Feb 13 2010
(PARI) concat(0, Vec(24*x^2/((2*x-1)*(6*x-1)) + O(x^30))) \\ Colin Barker, Oct 20 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Dec 25 2001
STATUS
approved