A235885 - OEIS

%I #6 May 03 2024 14:55:46

%S 40,232,1096,4744,19720,80392,324616,1304584,5230600,20946952,

%T 83836936,335446024

%N Number of (n+1) X (n+1) 0..3 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2 X 2 subblock.

%C Diagonal of A235893.

%F Empirical: a(n) = 7*a(n-1) -14*a(n-2) +8*a(n-3).

%e Some solutions for n=4

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

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

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

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

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

%Y Cf. A235893.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 16 2014