Number of integers <= 2^n of form 4 x^2 + 4 x y + 5 y^2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =7a(6) =14a(7) =24a(8) =43a(9) =82a(10) =149a(11) =284a(12) =534a(13) =1015a(14) =1937a(15) =3713a(16) =7136a(17) =13759a(18) =26597a(19) =51537a(20) =100045a(21) =194586a(22) =378987a(23) =739161a(24) =1443465a(25) =2821923a(26) =5522689a(27) =10818037a(28) =21208747a(29) =41612533