A066406 a(n) = 2^n*(3^n-3).

0, 24, 192, 1248, 7680, 46464, 279552, 1678848, 10076160, 60463104, 362790912, 2176770048, 13060669440, 78364114944, 470184886272, 2821109710848, 16926659051520, 101559955881984, 609359738437632, 3656158436917248, 21936950634086400, 131621703829684224

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

Sequence in context: A305166 A128960 A047057 * A271432 A042114 A220296

Adjacent sequences: A066403 A066404 A066405 * A066407 A066408 A066409

Keyword

nonn,easy

Author

N. J. A. Sloane, Dec 25 2001

Status

approved