A195641 - OEIS

%I #9 May 17 2020 01:41:03

%S 1,1,3,19,391,25532,5536654,4102276124,10576325574496,

%T 96132191056438654,3112190512707436846248,361888107612909923618319047,

%U 152218183506656720143679173709254,233008581159686014846657554273887832751

%N Number of lower triangles of an n X n 0..5 array with all row sums equal to the length of the row and all column sums equal to the length of the column.

%e Some solutions for n=5:

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

%e ..0.2........1.1........0.2........0.2........2.0........1.1........0.2

%e ..0.1.2......0.1.2......0.2.1......2.1.0......2.1.0......0.1.2......1.0.2

%e ..3.1.0.0....2.1.1.0....4.0.0.0....1.0.2.1....0.3.1.0....2.2.0.0....2.1.0.1

%e ..1.0.1.2.1..1.1.0.2.1..0.0.2.2.1..1.1.1.1.1..0.0.2.2.1..1.0.1.2.1..1.1.1.1.1

%Y Column 5 of A195644.

%K nonn

%O 1,3

%A _R. H. Hardin_, Sep 21 2011

%E a(12)-a(14) from _Andrew Howroyd_, May 16 2020