Number of nX2 0..3 arrays with rows and columns in nondecreasing order.

Terms

a(0) =10a(1) =86a(2) =561a(3) =2861a(4) =12068a(5) =43947a(6) =142376a(7) =419213a(8) =1139569a(9) =2894178a(10) =6931366a(11) =15770131a(12) =34291532a(13) =71619470a(14) =144269412a(15) =281284873a(16) =532422712a(17) =980922994a(18) =1763049635a(19) =3097467201a(20) =5328692624a(21) =8990408705a(22) =14896447100a(23) =24269860485