cp's OEIS Frontend

A218645 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random 0..3 n X 2 array.

%I A218645 #7 Jul 24 2018 09:49:41
%S A218645 4,16,66,292,1280,5644,24782,108940,478862,2104866,9252000,40667620,
%T A218645 178756504,785732636,3453724976,15181011874,66728857148,293309853452,
%U A218645 1289257359676,5666991817956,24909531073894,109491024206644
%N A218645 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random 0..3 n X 2 array.
%C A218645 Column 2 of A218651.
%H A218645 R. H. Hardin, <a href="/A218645/b218645.txt">Table of n, a(n) for n = 1..210</a>
%F A218645 Empirical: a(n) = 2*a(n-1) + 7*a(n-2) + 12*a(n-3) + 14*a(n-4) + 7*a(n-5) - 2*a(n-6) - 3*a(n-7) - a(n-8).
%F A218645 Empirical g.f.: 2*x*(2 + 4*x + 3*x^2 - 7*x^4 - 2*x^5 + x^6 + x^7) / (1 - 2*x - 7*x^2 - 12*x^3 - 14*x^4 - 7*x^5 + 2*x^6 + 3*x^7 + x^8). - _Colin Barker_, Jul 24 2018
%e A218645 Some solutions for n=3:
%e A218645 ..2..2....1..1....2..1....3..2....3..3....3..3....3..2....3..3....0..0....3..3
%e A218645 ..2..2....1..3....1..1....1..1....3..1....2..0....2..2....3..0....0..0....3..3
%e A218645 ..2..2....3..3....1..1....1..1....1..1....0..0....2..2....0..0....0..1....3..3
%Y A218645 Cf. A218651.
%K A218645 nonn
%O A218645 1,1
%A A218645 _R. H. Hardin_, Nov 03 2012