Number of simple imperfect squared rectangles of order n up to symmetry.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =1a(9) =0a(10) =0a(11) =9a(12) =34a(13) =104a(14) =283a(15) =953a(16) =3029a(17) =9513a(18) =30359a(19) =98969a(20) =323646a(21) =1080659a(22) =3668432a(23) =12608491a(24) =43745771a(25) =153812801