A209851 - OEIS

%I #9 Jul 13 2018 08:19:53

%S 25,182,1308,9455,68201,492373,3553425,25648639,185120173,1336151135,

%T 9643879893,69606629219,502398343961,3626155026415,26172443105853,

%U 188904494286595,1363453261197601,9840977730403175,71029086440088981

%N 1/4 the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having one or four distinct clockwise edge differences.

%C Column 1 of A209858.

%H R. H. Hardin, <a href="/A209851/b209851.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) + 29*a(n-2) - 28*a(n-3) - 110*a(n-4) + 82*a(n-5) - 8*a(n-6).

%F Empirical g.f.: x*(25 + 82*x - 145*x^2 - 355*x^3 + 295*x^4 - 32*x^5) / (1 - 4*x - 29*x^2 + 28*x^3 + 110*x^4 - 82*x^5 + 8*x^6). - _Colin Barker_, Jul 13 2018

%e Some solutions for n=4:

%e ..1..1....2..2....1..0....2..0....3..3....0..2....0..0....2..0....0..2....0..1

%e ..1..1....2..2....0..2....3..0....0..1....0..3....1..3....2..3....0..3....0..3

%e ..3..0....3..0....0..3....2..0....2..3....0..1....2..1....2..0....2..2....0..1

%e ..1..1....0..1....1..3....3..1....2..0....2..3....0..2....2..3....3..0....3..0

%e ..1..1....1..3....1..0....1..2....1..2....2..0....3..3....0..2....0..1....1..1

%Y Cf. A209858.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 14 2012