%I #8 Jan 16 2017 14:06:02
%S 1,6,27,92,267,678,1561,3312,6582,12372,22194,38232,63594,102564,
%T 160974,246576,369567,543114,784069,1113684,1558557,2151578,2933151,
%U 3952416,5268796,6953544,9091668,11783856,15148836,19325736,24476940,30790944,38485773,47812398
%N Number of 2 X n matrices over GF(3) under row and column permutations.
%H Colin Barker, <a href="/A052267/b052267.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (6,-12,2,27,-36,0,36,-27,-2,12,-6,1).
%F G.f.: (3*x^2+1) /((1-x^2)^3*(1-x)^6).
%F a(n) = ((315*(475+37*(-1)^n) + 6*(54959+945*(-1)^n)*n + (298618+630*(-1)^n)*n^2 + 150528*n^3 + 46788*n^4 + 9156*n^5 + 1092*n^6 + 72*n^7 + 2*n^8)) / 161280. - _Colin Barker_, Jan 16 2017
%o (PARI) Vec((3*x^2+1) / ((1-x^2)^3*(1-x)^6) + O(x^40)) \\ _Colin Barker_, Jan 16 2017
%Y Cf. A002623, A002727.
%K nonn,easy
%O 0,2
%A _Vladeta Jovovic_, Feb 04 2000