A227253 - OEIS

%I #4 Jul 04 2013 06:44:20

%S 4,9,36,134,450,1353,3722,9529,22957,52447,114282,238618,479284,

%T 929223,1744166,3178057,5634919,9743313,16461342,27222342,44134038,

%U 70247085,109912626,169252849,256773585,384153835,567253826,827390858,1192940904

%N Number of nX3 binary arrays indicating whether each 2X2 subblock of a larger binary array has lexicographically nondecreasing rows and columns, for some larger (n+1)X4 binary array with rows and columns of the latter in lexicographically nondecreasing order

%C Column 3 of A227256

%H R. H. Hardin, <a href="/A227253/b227253.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (1/9979200)*n^11 - (1/453600)*n^10 + (1/11340)*n^9 - (71/60480)*n^8 + (163/11200)*n^7 - (251/2700)*n^6 + (49501/90720)*n^5 - (319397/181440)*n^4 + (486707/113400)*n^3 + (34133/25200)*n^2 - (238061/6930)*n + 65 for n>3

%e Some solutions for n=4

%e ..1..1..1....1..1..1....1..1..1....1..0..0....1..1..1....1..1..0....1..0..0

%e ..1..0..0....1..0..0....1..1..0....0..1..1....1..1..0....1..0..1....0..1..1

%e ..0..1..1....0..1..1....1..0..1....0..1..0....1..1..0....1..0..0....1..1..0

%e ..1..1..0....1..1..1....0..0..1....1..1..0....1..0..0....1..0..0....1..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Jul 04 2013