A052280 Number of 4 X 4 stochastic matrices under row and column permutations.

1, 1, 5, 12, 43, 106, 321, 787, 1960, 4354, 9386, 18790, 36362, 66789, 118936, 203840, 340195, 551192, 873343, 1351457, 2052221, 3056798, 4480565, 6462678, 9194098, 12902867, 17892986, 24524478, 33265476, 44666016, 59426834, 78364873, 102502765, 133024660, 171390035, 219278224

Offset: 0

Author

Vladeta Jovovic, Feb 06 2000

Keywords

• nonn

Examples

			There are 5 nonisomorphic 4 X 4 matrices with row and column sums 2:
[0 0 0 2] [0 0 0 2] [0 0 0 2] [0 0 1 1] [0 0 1 1]
[0 0 2 0] [0 0 2 0] [0 1 1 0] [0 0 1 1] [0 1 0 1]
[0 2 0 0] [1 1 0 0] [1 0 1 0] [1 1 0 0] [1 0 1 0]
[2 0 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0]
		

Crossrefs

Row n=4 of A333733.

Cf. A001496, A052281, A052282.

Extensions

Terms a(9) and beyond from Andrew Howroyd, Apr 04 2020