A252923 - OEIS

%I #11 Feb 07 2019 15:24:16

%S 0,0,1,615,84910,8241540,759337545,73117894428,7578889491370,

%T 848729993032718,102072779621746876,13069744040275286234,

%U 1766655687081261435255,250232365919081938956865,36910187948533534644694094

%N Number of n X n nonnegative integer arrays with upper left 0 and lower right n+n-6 and value increasing by 0 or 1 with every step right or down.

%H Alois P. Heinz, <a href="/A252923/b252923.txt">Table of n, a(n) for n = 1..20</a> (first 15 terms from R. H. Hardin)

%e Some solutions for n=4

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

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

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

%e ..1..1..2..2....1..2..2..2....1..1..2..2....1..1..1..2....1..2..2..2

%Y Diagonal of A252930.

%K nonn

%O 1,4

%A _R. H. Hardin_, Dec 24 2014