Number of 3 X 3 0..n arrays with row and column sums equal.

Terms

a(0) =14a(1) =87a(2) =340a(3) =1001a(4) =2442a(5) =5215a(6) =10088a(7) =18081a(8) =30502a(9) =48983a(10) =75516a(11) =112489a(12) =162722a(13) =229503a(14) =316624a(15) =428417a(16) =569790a(17) =746263a(18) =964004a(19) =1229865a(20) =1551418a(21) =1936991a(22) =2395704a(23) =2937505a(24) =3573206a(25) =4314519a(26) =5174092a(27) =6165545a(28) =7303506a(29) =8603647