Numbers z such that x*(x+1) + y*(y+1) = z*(z+1) is solvable in positive integers x,y.

Terms

a(0) =3a(1) =6a(2) =8a(3) =10a(4) =11a(5) =13a(6) =15a(7) =16a(8) =18a(9) =20a(10) =21a(11) =23a(12) =26a(13) =27a(14) =28a(15) =31a(16) =33a(17) =36a(18) =37a(19) =38a(20) =40a(21) =41a(22) =43a(23) =44a(24) =45a(25) =46a(26) =48a(27) =49a(28) =51a(29) =52