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

Terms

a(0) =1a(1) =1a(2) =5a(3) =12a(4) =43a(5) =106a(6) =321a(7) =787a(8) =1960a(9) =4354a(10) =9386a(11) =18790a(12) =36362a(13) =66789a(14) =118936a(15) =203840a(16) =340195a(17) =551192a(18) =873343a(19) =1351457a(20) =2052221a(21) =3056798a(22) =4480565a(23) =6462678a(24) =9194098a(25) =12902867a(26) =17892986a(27) =24524478a(28) =33265476a(29) =44666016