Number of concave kites (darts or arrowheads) on an n X n grid (or geoboard).

Terms

a(0) =0a(1) =0a(2) =8a(3) =64a(4) =292a(5) =916a(6) =2344a(7) =5048a(8) =10096a(9) =18296a(10) =31400a(11) =50752a(12) =79308a(13) =118876a(14) =173768a(15) =246096a(16) =342256a(17) =465064a(18) =622904a(19) =818552a(20) =1063756a(21) =1361564a(22) =1725432a(23) =2159384a(24) =2682944a(25) =3298568a(26) =4027776a(27) =4873600