Number of nonsquare simple 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) =3a(9) =6a(10) =22a(11) =76a(12) =246a(13) =848a(14) =2889a(15) =9964a(16) =34440a(17) =119875a(18) =420525a(19) =1482802a(20) =5254679a(21) =18713933a(22) =66968081a(23) =240735712