A213795 Number of n X n 0..3 symmetric arrays with every row summing to floor(n*3/2).

1, 1, 4, 29, 880, 87932, 34725760, 46259653191, 250599609089536, 4664255347861848000, 359514810915617810737152, 96221422835240936091862618254, 107926925135028470351157750883132800, 423270762332675097186733226425581010359872

Offset: 0

Author

R. H. Hardin, Jun 20 2012

Keywords

• nonn

Examples

			Some solutions for n=4
..0..1..2..3....0..1..2..3....3..1..0..2....2..1..1..2....1..3..0..2
..1..0..2..3....1..2..1..2....1..1..2..2....1..2..1..2....3..1..1..1
..2..2..2..0....2..1..2..1....0..2..2..2....1..1..2..2....0..1..2..3
..3..3..0..0....3..2..1..0....2..2..2..0....2..2..2..0....2..1..3..0
		

Crossrefs

Column 3 of A213800.

Extensions

a(0)=1 prepended and terms a(9) and beyond from Andrew Howroyd, Apr 07 2020