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

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =7a(6) =14a(7) =25a(8) =45a(9) =84a(10) =154a(11) =290a(12) =549a(13) =1043a(14) =1990a(15) =3820a(16) =7352a(17) =14198a(18) =27473a(19) =53327a(20) =103697a(21) =201926a(22) =393781a(23) =769123a(24) =1503776a(25) =2943595a(26) =5767727a(27) =11310982a(28) =22200249a(29) =43604981