%I #8 Jun 05 2018 11:32:52

%S 8281,254359,7501753,222645367,6601376089,195759462871,5804976472057,

%T 172139217677623,5104567195084441,151369391916622999,

%U 4488665070837227833,133105602855424669687,3947075851161154183129,117045469473077458995031

%N Number of (n+1) X 3 0..6 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

%C Column 2 of A203887.

%H R. H. Hardin, <a href="/A203881/b203881.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 25*a(n-1) +138*a(n-2).

%F Empirical g.f.: 49*x*(169 + 966*x) / (1 - 25*x - 138*x^2). - _Colin Barker_, Jun 05 2018

%e Some solutions for n=4:

%e ..0..5..2....4..1..5....4..0..4....1..2..1....2..0..1....0..0..5....4..5..3

%e ..5..0..5....5..4..1....1..4..3....1..1..5....2..2..0....5..0..0....3..4..5

%e ..2..5..6....2..5..4....5..1..4....5..1..1....6..2..2....3..5..0....1..3..4

%e ..3..2..5....5..1..5....6..5..1....3..5..1....3..6..2....1..3..5....1..1..3

%e ..3..3..2....3..5..5....4..6..5....2..3..5....5..3..6....1..1..3....1..6..1

%Y Cf. A203887.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 07 2012