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

Terms

a(0) =1a(1) =5a(2) =7a(3) =9a(4) =17a(5) =15a(6) =21a(7) =21a(8) =25a(9) =35a(10) =29a(11) =37a(12) =35a(13) =45a(14) =45a(15) =43a(16) =57a(17) =57a(18) =57a(19) =59a(20) =57a(21) =73a(22) =71a(23) =73a(24) =73a(25) =85a(26) =83a(27) =81a(28) =93a(29) =87