Number of Gaussian integers z=a+bi satisfying |z|<=n, a>=0, 0<=b<a.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =7a(5) =11a(6) =15a(7) =20a(8) =26a(9) =33a(10) =41a(11) =49a(12) =57a(13) =68a(14) =79a(15) =91a(16) =102a(17) =115a(18) =129a(19) =144a(20) =160a(21) =175a(22) =193a(23) =210a(24) =228a(25) =249a(26) =269a(27) =290a(28) =311a(29) =333