Number of positive integers <= 2^n of form 7 x^2 + 9 y^2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =4a(6) =9a(7) =16a(8) =30a(9) =54a(10) =102a(11) =190a(12) =360a(13) =688a(14) =1313a(15) =2535a(16) =4889a(17) =9464a(18) =18376a(19) =35741a(20) =69623a(21) =135899a(22) =265500a(23) =519498a(24) =1017399a(25) =1994552a(26) =3913769a(27) =7685870a(28) =15104369a(29) =29704016