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