a(n)=number of Gaussian integers z=a+bi satisfying n-1/2<|z|<=n+1/2, a>=0, 0<=b<a.

Terms

a(0) =0a(1) =1a(2) =2a(3) =2a(4) =4a(5) =4a(6) =5a(7) =5a(8) =6a(9) =9a(10) =7a(11) =9a(12) =9a(13) =11a(14) =11a(15) =11a(16) =14a(17) =14a(18) =14a(19) =15a(20) =14a(21) =18a(22) =18a(23) =18a(24) =18a(25) =21a(26) =21a(27) =20a(28) =23a(29) =22