A214012 - OEIS

%I #8 Jul 03 2012 08:43:56

%S 271,7722,85639,564041,2663506,9976732,31499434,87205393,217519577,

%T 498458246,1064675833,2143185161,4101100212,7511389208,13241320196,

%U 22569031649,37334466803,60131772546,94551181659,145479371081

%N Number of 3X3 nonnegative integer matrices with row and column i=1..3 having sum <= i*n

%C Row 3 of A214011

%H R. H. Hardin, <a href="/A214012/b214012.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = (n+3) *(n+2) *(n+1) *(3493*n^6 +23853*n^5 +62185*n^4 +81783*n^3 +58531*n^2 +22470*n +3780)/22680;

%e Some solutions for n=3

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

%e ..2..0..0....2..1..0....0..6..0....1..2..0....1..0..0....0..0..0....0..1..0

%e ..0..6..0....0..0..5....0..0..9....2..1..0....0..3..4....0..4..0....1..2..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Jun 30 2012