A062156 Number of n X n matrices over {0,1,2} with all row and column sums equal to 1 or 2.

1, 2, 13, 189, 4842, 190080, 10520010, 777018690, 73646397720, 8696221929360, 1249994376199800, 214673857998276600, 43377963701592920400, 10180798532673708139200, 2745082427076790292091600, 842339587833332705318202000, 291745985923439508815578224000

Offset: 0

Author

Vladeta Jovovic, Jun 06 2001

Keywords

• easy
• nonn

Examples

			There are 13 2 X 2 matrices over {0,1,2} with all row and column sums equal to 1 or 2, cf. A062154.
		

References

• I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..100

Crossrefs

Main diagonal of A062154.

Cf. A062155.

Extensions

Terms a(15) and beyond from Andrew Howroyd, Feb 03 2021