cp's OEIS Frontend

A274890 Number of n X 3 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2.

%I A274890 #8 Jan 31 2019 08:07:02
%S A274890 2,12,16,38,84,192,436,990,2253,5121,11645,26483,60215,136936,311381,
%T A274890 708076,1610154,3661438,8326047,18933223,43053720,97903198,222629593,
%U A274890 506254676,1151211539,2617828789,5952883022,13536720098,30782192928
%N A274890 Number of n X 3 0..2 arrays with no element equal to any value at offset (0,-1) (-1,-1) or (-2,0) and new values introduced in order 0..2.
%H A274890 R. H. Hardin, <a href="/A274890/b274890.txt">Table of n, a(n) for n = 1..210</a>
%F A274890 Empirical: a(n) = a(n-1) + 4*a(n-2) - 6*a(n-4) - a(n-5) + 4*a(n-6) - a(n-8) for n>10.
%F A274890 Empirical g.f.: x*(2 + 10*x - 4*x^2 - 26*x^3 - 6*x^4 + 30*x^5 + 8*x^6 - 18*x^7 - x^8 + 4*x^9) / ((1 - x)*(1 + x)*(1 - x - 3*x^2 - x^3 + 3*x^4 - x^6)). - _Colin Barker_, Jan 31 2019
%e A274890 Some solutions for n=4:
%e A274890 ..0..1..0. .0..1..2. .0..1..2. .0..1..2. .0..1..2. .0..1..0. .0..1..2
%e A274890 ..2..1..2. .1..2..0. .0..1..0. .0..1..0. .1..2..0. .1..2..0. .0..1..2
%e A274890 ..1..0..2. .1..2..1. .1..2..0. .1..2..0. .1..2..0. .1..0..1. .1..2..0
%e A274890 ..1..0..1. .2..0..1. .2..0..1. .1..2..1. .2..0..1. .2..0..1. .1..2..0
%Y A274890 Column 3 of A274895.
%K A274890 nonn
%O A274890 1,1
%A A274890 _R. H. Hardin_, Jul 10 2016