A274751 - OEIS

%I #8 Jan 30 2019 15:26:53

%S 4,27,144,813,4554,25585,143634,806695,4529786,25438375,142850048,

%T 802197187,4504820208,25297392889,142060454416,797757713921,

%U 4479903521254,25157436233205,141274594599246,793344420605515

%N Number of 4 X n 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2.

%H R. H. Hardin, <a href="/A274751/b274751.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) + 20*a(n-2) + 10*a(n-3) - 44*a(n-4) - 20*a(n-5) + 31*a(n-6) + 2*a(n-7) - 4*a(n-8).

%F Empirical g.f.: x*(4 + 19*x + 10*x^2 - 55*x^3 - 46*x^4 + 45*x^5 + 6*x^6 - 6*x^7) / ((1 + x - x^2)*(1 - 3*x - 16*x^2 + 3*x^3 + 25*x^4 - 2*x^5 - 4*x^6)). - _Colin Barker_, Jan 30 2019

%e Some solutions for n=4:

%e ..0..1..0..1. .0..1..0..2. .0..1..0..1. .0..1..0..2. .0..1..0..1

%e ..2..0..1..0. .1..2..1..0. .2..0..1..0. .1..0..2..0. .1..2..1..2

%e ..0..2..0..1. .0..1..2..1. .0..1..0..1. .0..1..0..1. .2..0..2..1

%e ..2..1..2..0. .1..0..1..0. .1..2..1..0. .2..0..2..0. .0..1..0..2

%Y Row 4 of A274749.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jul 04 2016