A223943 - OEIS

%I #7 Dec 27 2023 00:18:23

%S 2,9,54,321,1821,9919,52532,272997,1401993,7150718,36352875,184670276,

%T 938969921,4783571827,24431153268,125119394092

%N Number of n X n 0..1 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.

%C Diagonal of A223949.

%e Some solutions for n=3

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

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

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

%Y Cf. A223949.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 29 2013