Number of inequivalent (mod D_4) ways to place 2 nonattacking knights on an n X n board.

Terms

a(0) =2a(1) =7a(2) =18a(3) =43a(4) =83a(5) =156a(6) =257a(7) =418a(8) =624a(9) =925a(10) =1292a(11) =1797a(12) =2393a(13) =3178a(14) =4083a(15) =5236a(16) =6542a(17) =8163a(18) =9974a(19) =12175a(20) =14607a(21) =17512a(22) =20693a(23) =24438a(24) =28508a(25) =33241a(26) =38352a(27) =44233a(28) =50549a(29) =57750