A274854 - OEIS

%I #8 Jan 31 2019 08:06:44

%S 4,27,43,118,330,923,2585,7253,20368,57205,160656,451182,1267101,

%T 3558565,9994005,28067514,78825751,221376890,621722366,1746066251,

%U 4903711869,13771751157,38677054168,108621953977,305057588980,856734105714

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

%H R. H. Hardin, <a href="/A274854/b274854.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) - 9*a(n-2) + 10*a(n-3) - 6*a(n-4) + a(n-5) for n>7.

%F Empirical g.f.: x*(4 + 7*x - 56*x^2 + 106*x^3 - 119*x^4 + 63*x^5 - 9*x^6) / ((1 - x)*(1 - 4*x + 5*x^2 - 5*x^3 + x^4)). - _Colin Barker_, Jan 31 2019

%e Some solutions for n=4:

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

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

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

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

%Y Column 4 of A274858.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jul 09 2016