cp's OEIS Frontend

A252869 Number of n X n nonnegative integer arrays with upper left 0 and lower right 2n-4 and value increasing by 0 or 1 with every step right or down.

%I A252869 #15 Feb 11 2019 15:30:32
%S A252869 0,1,44,615,7313,85801,1030330,12742873,161937617,2105918045,
%T A252869 27918122131,376111502977,5136280530303,70961632168027,
%U A252869 990271171218092,13940676224604419,197768060575469207,2824828302263709187,40595088350375470407,586585037283553891311
%N A252869 Number of n X n nonnegative integer arrays with upper left 0 and lower right 2n-4 and value increasing by 0 or 1 with every step right or down.
%e A252869 Some solutions for n=3
%e A252869 ..0..0..1....0..0..0....0..0..1....0..1..1....0..1..1....0..1..2....0..1..2
%e A252869 ..1..1..1....0..0..1....0..0..1....1..1..2....0..1..1....0..1..2....1..2..2
%e A252869 ..1..2..2....1..1..2....0..1..2....1..2..2....1..2..2....1..1..2....2..2..2
%Y A252869 Main diagonal of A252876.
%Y A252869 Column d=2 of A323849.
%K A252869 nonn
%O A252869 1,3
%A A252869 _R. H. Hardin_, Dec 24 2014
%E A252869 a(16)-a(20) from _Alois P. Heinz_, Feb 07 2019