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

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =12a(5) =21a(6) =38a(7) =68a(8) =124a(9) =229a(10) =428a(11) =806a(12) =1530a(13) =2919a(14) =5591a(15) =10750a(16) =20730a(17) =40077a(18) =77653a(19) =150752a(20) =293161a(21) =570963a(22) =1113524a(23) =2174315a(24) =4250367a(25) =8317036a(26) =16289636a(27) =31931697a(28) =62642861a(29) =122980015