A213804 Number of 6 X 6 0..n symmetric arrays with all rows summing to 3*n.

1, 1760, 526443, 34725760, 932587453, 13937940952, 138198204339, 1012226679296, 5875958390949, 28376054552968, 118033137259563, 433946033473016, 1438074947544977, 4362051703339832, 12258717265789491, 32233542519648928, 79941392042719253, 188248433874383736, 423266982431567911

Offset: 0

Author

R. H. Hardin, Jun 20 2012

Keywords

• nonn

Examples

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

Crossrefs

Row 6 of A213800.

Extensions

a(0)=1 prepended and terms a(12) and beyond from Andrew Howroyd, Apr 07 2020