%I #6 Dec 18 2015 18:18:53
%S 0,1,18,386,12200,608993,49489706,6648891794,1489334202216,
%T 558938851118771,352470525557050186,374131713336300308700,
%U 669158287926101914730400,2017974751792892883550074600
%N Number of n X n nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 1 and every value increasing by 0 or 1 with every step right, diagonally se or down
%C Diagonal of A252889
%H R. H. Hardin, <a href="/A252888/b252888.txt">Table of n, a(n) for n = 1..15</a>
%e Some solutions for n=4
%e ..0..0..1..1....0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..0
%e ..0..0..1..2....0..0..1..1....0..1..1..1....0..0..1..1....0..0..0..1
%e ..0..1..1..2....1..1..1..1....1..1..1..2....0..1..1..2....0..0..1..1
%e ..1..1..2..2....1..1..2..2....1..2..2..2....0..1..2..2....0..1..1..2
%K nonn
%O 1,3
%A _R. H. Hardin_, Dec 24 2014