Number of distinct products i*j with 0 <= i, j <= 2^n - 1.

Terms

a(0) =1a(1) =2a(2) =7a(3) =26a(4) =90a(5) =340a(6) =1238a(7) =4647a(8) =17578a(9) =67592a(10) =259768a(11) =1004348a(12) =3902357a(13) =15202050a(14) =59410557a(15) =232483840a(16) =911689012a(17) =3581049040a(18) =14081089288a(19) =55439171531a(20) =218457593223a(21) =861617935051