The pairs (x,y) such that (x^2 + y^2)/(x*y + 1) is a perfect square, i.e., 4.

Terms

a(0) =0a(1) =2a(2) =2a(3) =8a(4) =8a(5) =30a(6) =30a(7) =112a(8) =112a(9) =418a(10) =418a(11) =1560a(12) =1560a(13) =5822a(14) =5822a(15) =21728a(16) =21728a(17) =81090a(18) =81090a(19) =302632a(20) =302632a(21) =1129438a(22) =1129438a(23) =4215120a(24) =4215120a(25) =15731042a(26) =15731042a(27) =58709048a(28) =58709048a(29) =219105150