Number of positive integers <= 2^n of form 3 x^2 + 6 y^2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =7a(6) =13a(7) =23a(8) =43a(9) =78a(10) =144a(11) =269a(12) =502a(13) =945a(14) =1794a(15) =3414a(16) =6537a(17) =12559a(18) =24195a(19) =46751a(20) =90539a(21) =175693a(22) =341530a(23) =664965a(24) =1296520a(25) =2531118a(26) =4946995a(27) =9678777a(28) =18954593a(29) =37152384