Nullspace dimension of the periodic XX Heisenberg chain with n > 1 sites.

Terms

a(0) =2a(1) =2a(2) =10a(3) =2a(4) =14a(5) =2a(6) =60a(7) =20a(8) =74a(9) =2a(10) =386a(11) =2a(12) =434a(13) =346a(14) =2160a(15) =2a(16) =6124a(17) =2a(18) =13106a(19) =2866a(20) =15554a(21) =2a(22) =122036a(23) =2312a(24) =93314a(25) =20000a(26) =467426a(27) =2a(28) =3475258a(29) =2