Related to population of numbers of form x^2 + y^2.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =10a(5) =19a(6) =35a(7) =62a(8) =118a(9) =219a(10) =414a(11) =783a(12) =1497a(13) =2860a(14) =5503a(15) =10593a(16) =20471a(17) =39637a(18) =76918a(19) =149501a(20) =291115a(21) =567581a(22) =1108022a(23) =2165621a(24) =4237085a(25) =8297727a(26) =16264207a(27) =31904254a(28) =62630372a(29) =123031586