cp's OEIS Frontend

A221667 Sum of neighbor maps: number of 2 X n binary arrays indicating the locations of corresponding elements equal to the sum mod 3 of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 2 X n array.

%I A221667 #8 Aug 10 2018 09:14:15
%S A221667 4,12,64,256,992,4096,16384,65344,262144,1048576,4193280,16777216,
%T A221667 67108864,268430336,1073741824,4294967296,17179844608,68719476736,
%U A221667 274877906944,1099511513088,4398046511104,17592186044416,70368743653376
%N A221667 Sum of neighbor maps: number of 2 X n binary arrays indicating the locations of corresponding elements equal to the sum mod 3 of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 2 X n array.
%C A221667 Row 2 of A221666.
%H A221667 R. H. Hardin, <a href="/A221667/b221667.txt">Table of n, a(n) for n = 1..210</a>
%F A221667 Empirical: a(n) = 4*a(n-1) + 8*a(n-3) - 32*a(n-4) - 16*a(n-6) + 64*a(n-7).
%F A221667 Empirical g.f.: 4*x*(1 - x + 4*x^2 - 8*x^3 + 16*x^6) / ((1 - 4*x)*(1 - 4*x^3)^2). - _Colin Barker_, Aug 10 2018
%e A221667 Some solutions for n=3:
%e A221667 ..0..0..0....0..1..0....0..1..1....0..1..1....1..1..0....0..0..1....1..0..1
%e A221667 ..1..1..1....0..1..0....0..1..1....0..1..0....1..1..1....0..1..1....0..1..0
%Y A221667 Cf. A221666.
%K A221667 nonn
%O A221667 1,1
%A A221667 _R. H. Hardin_, Jan 21 2013