Number of positive integers <= 2^n of form x^2 + 12 y^2.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =6a(5) =9a(6) =17a(7) =30a(8) =54a(9) =98a(10) =183a(11) =341a(12) =645a(13) =1220a(14) =2327a(15) =4451a(16) =8555a(17) =16489a(18) =31859a(19) =61717a(20) =119779a(21) =232919a(22) =453584a(23) =884544a(24) =1727213a(25) =3376505a(26) =6607371a(27) =12942012a(28) =25371540a(29) =49777187