Number of different fixed (possibly) disconnected tetrominoes bounded tightly by an n X n square.

Terms

a(0) =0a(1) =1a(2) =70a(3) =425a(4) =1426a(5) =3577a(6) =7526a(7) =14065a(8) =24130a(9) =38801a(10) =59302a(11) =87001a(12) =123410a(13) =170185a(14) =229126a(15) =302177a(16) =391426a(17) =499105a(18) =627590a(19) =779401a(20) =957202a(21) =1163801a(22) =1402150a(23) =1675345a(24) =1986626a(25) =2339377a(26) =2737126a(27) =3183545a(28) =3682450a(29) =4237801