A052280 - OEIS

%I #9 Apr 04 2020 17:42:26

%S 1,1,5,12,43,106,321,787,1960,4354,9386,18790,36362,66789,118936,

%T 203840,340195,551192,873343,1351457,2052221,3056798,4480565,6462678,

%U 9194098,12902867,17892986,24524478,33265476,44666016,59426834,78364873,102502765,133024660,171390035,219278224

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

%e There are 5 nonisomorphic 4 X 4 matrices with row and column sums 2:

%e [0 0 0 2] [0 0 0 2] [0 0 0 2] [0 0 1 1] [0 0 1 1]

%e [0 0 2 0] [0 0 2 0] [0 1 1 0] [0 0 1 1] [0 1 0 1]

%e [0 2 0 0] [1 1 0 0] [1 0 1 0] [1 1 0 0] [1 0 1 0]

%e [2 0 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0]

%Y Row n=4 of A333733.

%Y Cf. A001496, A052281, A052282.

%K nonn

%O 0,3

%A _Vladeta Jovovic_, Feb 06 2000

%E Terms a(9) and beyond from _Andrew Howroyd_, Apr 04 2020